{"id":15583,"date":"2024-01-14T07:19:10","date_gmt":"2024-01-14T03:49:10","guid":{"rendered":"https:\/\/rasanegar.com\/blog\/%d8%ac%d8%a7%d9%88%d8%a7-%d8%a7%d8%b3%da%a9%d8%b1%db%8c%d9%be%d8%aa-%d8%a8%d8%b1%d8%b1%d8%b3%db%8c-%da%a9%d9%86%db%8c%d8%af-%da%a9%d9%87-%d8%a2%db%8c%d8%a7-%d9%85%d8%aa%d8%ba%db%8c%d8%b1-%d8%aa%d8%b9\/"},"modified":"2024-01-14T07:19:10","modified_gmt":"2024-01-14T03:49:10","slug":"%d8%ac%d8%a7%d9%88%d8%a7-%d8%a7%d8%b3%da%a9%d8%b1%db%8c%d9%be%d8%aa-%d8%a8%d8%b1%d8%b1%d8%b3%db%8c-%da%a9%d9%86%db%8c%d8%af-%da%a9%d9%87-%d8%a2%db%8c%d8%a7-%d9%85%d8%aa%d8%ba%db%8c%d8%b1-%d8%aa%d8%b9","status":"publish","type":"post","link":"https:\/\/rasanegaar.com\/blog\/%d8%ac%d8%a7%d9%88%d8%a7-%d8%a7%d8%b3%da%a9%d8%b1%db%8c%d9%be%d8%aa-%d8%a8%d8%b1%d8%b1%d8%b3%db%8c-%da%a9%d9%86%db%8c%d8%af-%da%a9%d9%87-%d8%a2%db%8c%d8%a7-%d9%85%d8%aa%d8%ba%db%8c%d8%b1-%d8%aa%d8%b9\/","title":{"rendered":"\u062c\u0627\u0648\u0627 \u0627\u0633\u06a9\u0631\u06cc\u067e\u062a: \u0628\u0631\u0631\u0633\u06cc \u06a9\u0646\u06cc\u062f \u06a9\u0647 \u0622\u06cc\u0627 \u0645\u062a\u063a\u06cc\u0631 \u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647 \u06cc\u0627 \u062a\u0647\u06cc \u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647 \u0627\u0633\u062a \u0648 \u0645\u0642\u0627\u062f\u06cc\u0631 \u062a\u0647\u06cc \u0647\u0645\u06cc\u0634\u0647 \u0628\u0647 \u0635\u0648\u0631\u062a \u0645\u062e\u0641\u06cc\u0627\u0646\u0647 \u0648\u0627\u0631\u062f \u062c\u0631\u06cc\u0627\u0646 \u06a9\u062f \u0645\u06cc \u0634\u0648\u0646\u062f.  \u0686\u0647 \u0645\u0627 \u06cc\u06a9 \u0645\u0631\u062c\u0639 \u0631\u0627 \u0627\u0632 \u0637\u0631\u06cc\u0642 \u0639\u0648\u0627\u0631\u0636 \u062c\u0627\u0646\u0628\u06cc \u0627\u0632 \u062f\u0633\u062a \u062f\u0647\u06cc\u0645\u060c \u0641\u0631\u0627\u0645\u0648\u0634 \u06a9\u0646\u06cc\u0645 \u06cc\u06a9 \u0645\u062a\u063a\u06cc\u0631 \u0645\u0631\u062c\u0639 \u0631\u0627 \u0628\u0647 \u06cc\u06a9 \u0634\u06cc \u062f\u0631 \u062d\u0627\u0641\u0638\u0647 \u0627\u062e\u062a\u0635\u0627\u0635 \u062f\u0647\u06cc\u0645\u060c \u06cc\u0627 \u06cc\u06a9 \u067e\u0627\u0633\u062e \u062e\u0627\u0644\u06cc \u0627\u0632 \u06cc\u06a9 \u0645\u0646\u0628\u0639\u060c \u067e\u0627\u06cc\u06af\u0627\u0647 \u062f\u0627\u062f\u0647 \u06cc\u0627 API \u062f\u06cc\u06af\u0631 \u062f\u0631\u06cc\u0627\u0641\u062a \u06a9\u0646\u06cc\u0645 &#8211; \u0628\u0627\u06cc\u062f \u0628\u0627 \u0645\u0648\u0627\u0631\u062f \u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647 \u0645\u0642\u0627\u0628\u0644\u0647 \u06a9\u0646\u06cc\u0645&#8230;"},"content":{"rendered":"<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_85 counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\"><p class=\"ez-toc-title\" style=\"cursor:inherit\">\u0633\u0631\u0641\u0635\u0644\u0647\u0627\u06cc \u0645\u0637\u0644\u0628<\/p>\n<\/div><nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/rasanegaar.com\/blog\/%d8%ac%d8%a7%d9%88%d8%a7-%d8%a7%d8%b3%da%a9%d8%b1%db%8c%d9%be%d8%aa-%d8%a8%d8%b1%d8%b1%d8%b3%db%8c-%da%a9%d9%86%db%8c%d8%af-%da%a9%d9%87-%d8%a2%db%8c%d8%a7-%d9%85%d8%aa%d8%ba%db%8c%d8%b1-%d8%aa%d8%b9\/#%d9%85%d8%b9%d8%b1%d9%81%db%8c\" >\u0645\u0639\u0631\u0641\u06cc<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/rasanegaar.com\/blog\/%d8%ac%d8%a7%d9%88%d8%a7-%d8%a7%d8%b3%da%a9%d8%b1%db%8c%d9%be%d8%aa-%d8%a8%d8%b1%d8%b1%d8%b3%db%8c-%da%a9%d9%86%db%8c%d8%af-%da%a9%d9%87-%d8%a2%db%8c%d8%a7-%d9%85%d8%aa%d8%ba%db%8c%d8%b1-%d8%aa%d8%b9\/#%d8%aa%d9%81%d8%a7%d9%88%d8%aa_%d8%a8%db%8c%d9%86_%d8%aa%d8%b9%d8%b1%db%8c%d9%81_%d9%86%d8%b4%d8%af%d9%87_%d9%88_%d8%ae%d8%a7%d9%84%db%8c\" >\u062a\u0641\u0627\u0648\u062a \u0628\u06cc\u0646 \u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647 \u0648 \u062e\u0627\u0644\u06cc<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/rasanegaar.com\/blog\/%d8%ac%d8%a7%d9%88%d8%a7-%d8%a7%d8%b3%da%a9%d8%b1%db%8c%d9%be%d8%aa-%d8%a8%d8%b1%d8%b1%d8%b3%db%8c-%da%a9%d9%86%db%8c%d8%af-%da%a9%d9%87-%d8%a2%db%8c%d8%a7-%d9%85%d8%aa%d8%ba%db%8c%d8%b1-%d8%aa%d8%b9\/#%d8%a8%d8%b1%d8%b1%d8%b3%db%8c_%da%a9%d9%86%db%8c%d8%af_%da%a9%d9%87_%d8%a2%db%8c%d8%a7_%d9%85%d8%aa%d8%ba%db%8c%d8%b1_%d8%a7%d8%b3%d8%aa_%db%8c%d8%a7_%d8%ae%db%8c%d8%b1_%d8%aa%d8%b9%d8%b1%db%8c%d9%81_%d9%86%d8%b4%d8%af%d9%87_%db%8c%d8%a7_%d8%ae%d8%a7%d9%84%db%8c\" >\u0628\u0631\u0631\u0633\u06cc \u06a9\u0646\u06cc\u062f \u06a9\u0647 \u0622\u06cc\u0627 \u0645\u062a\u063a\u06cc\u0631 \u0627\u0633\u062a \u06cc\u0627 \u062e\u06cc\u0631 \u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647 \u06cc\u0627 \u062e\u0627\u0644\u06cc<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/rasanegaar.com\/blog\/%d8%ac%d8%a7%d9%88%d8%a7-%d8%a7%d8%b3%da%a9%d8%b1%db%8c%d9%be%d8%aa-%d8%a8%d8%b1%d8%b1%d8%b3%db%8c-%da%a9%d9%86%db%8c%d8%af-%da%a9%d9%87-%d8%a2%db%8c%d8%a7-%d9%85%d8%aa%d8%ba%db%8c%d8%b1-%d8%aa%d8%b9\/#_%d9%88_%d8%a7%d9%be%d8%b1%d8%a7%d8%aa%d9%88%d8%b1%d9%87%d8%a7\" >== \u0648 === \u0627\u067e\u0631\u0627\u062a\u0648\u0631\u0647\u0627<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/rasanegaar.com\/blog\/%d8%ac%d8%a7%d9%88%d8%a7-%d8%a7%d8%b3%da%a9%d8%b1%db%8c%d9%be%d8%aa-%d8%a8%d8%b1%d8%b1%d8%b3%db%8c-%da%a9%d9%86%db%8c%d8%af-%da%a9%d9%87-%d8%a2%db%8c%d8%a7-%d9%85%d8%aa%d8%ba%db%8c%d8%b1-%d8%aa%d8%b9\/#%d9%86%d9%88%d8%b9_%d8%a7%d9%be%d8%b1%d8%a7%d8%aa%d9%88%d8%b1\" >\u0646\u0648\u0639 \u0627\u067e\u0631\u0627\u062a\u0648\u0631<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/rasanegaar.com\/blog\/%d8%ac%d8%a7%d9%88%d8%a7-%d8%a7%d8%b3%da%a9%d8%b1%db%8c%d9%be%d8%aa-%d8%a8%d8%b1%d8%b1%d8%b3%db%8c-%da%a9%d9%86%db%8c%d8%af-%da%a9%d9%87-%d8%a2%db%8c%d8%a7-%d9%85%d8%aa%d8%ba%db%8c%d8%b1-%d8%aa%d8%b9\/#%d8%a7%d8%b3%d8%aa%d9%81%d8%a7%d8%af%d9%87_%d8%a7%d8%b2_lodash_%d8%a8%d8%b1%d8%a7%db%8c_%d8%a8%d8%b1%d8%b1%d8%b3%db%8c_%d8%a7%db%8c%d9%86%da%a9%d9%87_%d8%a2%db%8c%d8%a7_%d9%85%d8%aa%d8%ba%db%8c%d8%b1_%d8%a7%d8%b3%d8%aa_%db%8c%d8%a7_%d8%ae%db%8c%d8%b1_%d8%ae%d8%a7%d9%84%db%8c%d8%8c_%d8%aa%d8%b9%d8%b1%db%8c%d9%81_%d9%86%d8%b4%d8%af%d9%87_%db%8c%d8%a7_%d8%b5%d9%81%d8%b1\" >\u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u0627\u0632 Lodash \u0628\u0631\u0627\u06cc \u0628\u0631\u0631\u0633\u06cc \u0627\u06cc\u0646\u06a9\u0647 \u0622\u06cc\u0627 \u0645\u062a\u063a\u06cc\u0631 \u0627\u0633\u062a \u06cc\u0627 \u062e\u06cc\u0631 \u062e\u0627\u0644\u06cc\u060c \u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647 \u06cc\u0627 \u0635\u0641\u0631<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/rasanegaar.com\/blog\/%d8%ac%d8%a7%d9%88%d8%a7-%d8%a7%d8%b3%da%a9%d8%b1%db%8c%d9%be%d8%aa-%d8%a8%d8%b1%d8%b1%d8%b3%db%8c-%da%a9%d9%86%db%8c%d8%af-%da%a9%d9%87-%d8%a2%db%8c%d8%a7-%d9%85%d8%aa%d8%ba%db%8c%d8%b1-%d8%aa%d8%b9\/#lodash_%d8%b1%d8%a7_%d9%86%d8%b5%d8%a8_%d9%88_%d9%88%d8%a7%d8%b1%d8%af_%da%a9%d9%86%db%8c%d8%af\" >Lodash \u0631\u0627 \u0646\u0635\u0628 \u0648 \u0648\u0627\u0631\u062f \u06a9\u0646\u06cc\u062f<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/rasanegaar.com\/blog\/%d8%ac%d8%a7%d9%88%d8%a7-%d8%a7%d8%b3%da%a9%d8%b1%db%8c%d9%be%d8%aa-%d8%a8%d8%b1%d8%b1%d8%b3%db%8c-%da%a9%d9%86%db%8c%d8%af-%da%a9%d9%87-%d8%a2%db%8c%d8%a7-%d9%85%d8%aa%d8%ba%db%8c%d8%b1-%d8%aa%d8%b9\/#%d9%86%d8%aa%db%8c%d8%ac%d9%87\" >\u0646\u062a\u06cc\u062c\u0647<\/a><\/li><\/ul><\/nav><\/div>\n<span class=\"span-reading-time rt-reading-time\" style=\"display: block;\"><span class=\"rt-label rt-prefix\">\u0632\u0645\u0627\u0646 \u0644\u0627\u0632\u0645 \u0628\u0631\u0627\u06cc \u0645\u0637\u0627\u0644\u0639\u0647: <\/span> <span class=\"rt-time\"> 5<\/span> <span class=\"rt-label rt-postfix\">\u062f\u0642\u06cc\u0642\u0647<\/span><\/span><p> <br \/>\n<\/p>\n<div class=\"content\"><noscript><\/p>\n<style>.lazyload-placeholder { display: none;  }<\/style>\n<p><\/noscript><\/p>\n<h2 id=\"introduction\"><span class=\"ez-toc-section\" id=\"%d9%85%d8%b9%d8%b1%d9%81%db%8c\"><\/span>\u0645\u0639\u0631\u0641\u06cc<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><code>undefined<\/code>  \u0648 <code>null<\/code> \u0645\u0642\u0627\u062f\u06cc\u0631 \u0647\u0645\u06cc\u0634\u0647 \u0628\u0647 \u0635\u0648\u0631\u062a \u0645\u062e\u0641\u06cc\u0627\u0646\u0647 \u0648\u0627\u0631\u062f \u062c\u0631\u06cc\u0627\u0646 \u06a9\u062f \u0645\u06cc \u0634\u0648\u0646\u062f.  \u0686\u0647 \u0645\u0627 \u06cc\u06a9 \u0645\u0631\u062c\u0639 \u0631\u0627 \u0627\u0632 \u0637\u0631\u06cc\u0642 \u0639\u0648\u0627\u0631\u0636 \u062c\u0627\u0646\u0628\u06cc \u0627\u0632 \u062f\u0633\u062a \u062f\u0647\u06cc\u0645\u060c \u0641\u0631\u0627\u0645\u0648\u0634 \u06a9\u0646\u06cc\u0645 \u06cc\u06a9 \u0645\u062a\u063a\u06cc\u0631 \u0645\u0631\u062c\u0639 \u0631\u0627 \u0628\u0647 \u06cc\u06a9 \u0634\u06cc \u062f\u0631 \u062d\u0627\u0641\u0638\u0647 \u0627\u062e\u062a\u0635\u0627\u0635 \u062f\u0647\u06cc\u0645\u060c \u06cc\u0627 \u06cc\u06a9 \u067e\u0627\u0633\u062e \u062e\u0627\u0644\u06cc \u0627\u0632 \u06cc\u06a9 \u0645\u0646\u0628\u0639\u060c \u067e\u0627\u06cc\u06af\u0627\u0647 \u062f\u0627\u062f\u0647 \u06cc\u0627 API \u062f\u06cc\u06af\u0631 \u062f\u0631\u06cc\u0627\u0641\u062a \u06a9\u0646\u06cc\u0645 &#8211; \u0628\u0627\u06cc\u062f \u0628\u0627 \u0622\u0646 \u0645\u0642\u0627\u0628\u0644\u0647 \u06a9\u0646\u06cc\u0645. <code>undefined<\/code> \u0648 <code>null<\/code> \u0647\u0645\u06cc\u0634\u0647 \u0627\u0631\u0632\u0634 \u062f\u0627\u0631\u062f<\/p>\n<blockquote>\n<p>\u062f\u0631 \u0627\u06cc\u0646 \u0631\u0627\u0647\u0646\u0645\u0627\u06cc \u06a9\u0648\u062a\u0627\u0647\u060c \u0645\u0627 \u0646\u06af\u0627\u0647\u06cc \u0628\u0647 \u0686\u06af\u0648\u0646\u06af\u06cc \u0628\u0631\u0631\u0633\u06cc \u0627\u06cc\u0646\u06a9\u0647 \u0622\u06cc\u0627 \u06cc\u06a9 \u0645\u062a\u063a\u06cc\u0631 \u0627\u0633\u062a \u06cc\u0627 \u062e\u06cc\u0631\u060c \u062e\u0648\u0627\u0647\u06cc\u0645 \u062f\u0627\u0634\u062a <code>undefined<\/code> \u06cc\u0627 <code>null<\/code> \u062f\u0631 \u062c\u0627\u0648\u0627 \u0627\u0633\u06a9\u0631\u06cc\u067e\u062a<\/p>\n<\/blockquote>\n<h2 id=\"differencebetweenundefinedandnull\"><span class=\"ez-toc-section\" id=\"%d8%aa%d9%81%d8%a7%d9%88%d8%aa_%d8%a8%db%8c%d9%86_%d8%aa%d8%b9%d8%b1%db%8c%d9%81_%d9%86%d8%b4%d8%af%d9%87_%d9%88_%d8%ae%d8%a7%d9%84%db%8c\"><\/span>\u062a\u0641\u0627\u0648\u062a \u0628\u06cc\u0646 <em>\u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647<\/em> \u0648 <em>\u062e\u0627\u0644\u06cc<\/em><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p><code>undefined<\/code>  \u0648 <code>null<\/code> \u0645\u062a\u063a\u06cc\u0631\u0647\u0627 \u0627\u063a\u0644\u0628 \u062f\u0633\u062a \u0628\u0647 \u062f\u0633\u062a \u0647\u0645 \u0645\u06cc \u062f\u0647\u0646\u062f \u0648 \u0628\u0631\u062e\u06cc \u0627\u0632 \u0627\u06cc\u0646 \u0627\u0635\u0637\u0644\u0627\u062d\u0627\u062a \u0628\u0647 \u062c\u0627\u06cc \u06cc\u06a9\u062f\u06cc\u06af\u0631 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u0645\u06cc \u06a9\u0646\u0646\u062f.  \u0627\u06af\u0631\u0686\u0647 \u0628\u06cc\u0646 \u0622\u0646\u0647\u0627 \u062a\u0641\u0627\u0648\u062a \u0648\u062c\u0648\u062f \u062f\u0627\u0631\u062f:<\/p>\n<ul>\n<li><strong><em>\u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647<\/em><\/strong>  \u0645\u062a\u063a\u06cc\u0631\u06cc \u0627\u0633\u062a \u06a9\u0647 \u0628\u0647 \u0686\u06cc\u0632\u06cc \u0627\u0634\u0627\u0631\u0647 \u062f\u0627\u0631\u062f \u06a9\u0647 \u0648\u062c\u0648\u062f \u0646\u062f\u0627\u0631\u062f\u060c \u0648 \u0645\u062a\u063a\u06cc\u0631 \u0628\u0647 \u0639\u0646\u0648\u0627\u0646 \u0686\u06cc\u0632\u06cc \u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647 \u0627\u0633\u062a.<\/li>\n<li><strong><em>\u062e\u0627\u0644\u06cc<\/em><\/strong>  \u0645\u062a\u063a\u06cc\u0631\u06cc \u0627\u0633\u062a \u06a9\u0647 \u0627\u0633\u062a <em>\u062a\u0639\u0631\u06cc\u0641 \u0634\u062f\u0647 \u0627\u0633\u062a<\/em> \u0627\u0645\u0627 \u06cc\u06a9 \u0645\u0642\u062f\u0627\u0631 \u0631\u0627 \u0627\u0632 \u062f\u0633\u062a \u062f\u0627\u062f\u0647 \u0627\u0633\u062a.<\/li>\n<\/ul>\n<p>\u062a\u0641\u0627\u0648\u062a \u0628\u06cc\u0646 \u0627\u06cc\u0646 \u062f\u0648 \u0634\u0627\u06cc\u062f \u0627\u0632 \u0637\u0631\u06cc\u0642 \u06a9\u062f \u06a9\u0645\u06cc \u0648\u0627\u0636\u062d \u062a\u0631 \u0628\u0627\u0634\u062f:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-keyword\">let<\/span> a;\n<span class=\"hljs-built_in\">console<\/span>.log(a); <span class=\"hljs-comment\">\/\/ undefined<\/span>\n\n<span class=\"hljs-keyword\">let<\/span> b = <span class=\"hljs-literal\">null<\/span>;\n<span class=\"hljs-built_in\">console<\/span>.log(b); <span class=\"hljs-comment\">\/\/ null<\/span>\n<\/code><\/pre>\n<p><code>a<\/code>  \u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647 \u0627\u0633\u062a &#8211; \u0628\u0647 \u0647\u06cc\u0686 \u0686\u06cc\u0632 \u0627\u062e\u062a\u0635\u0627\u0635 \u062f\u0627\u062f\u0647 \u0646\u0645\u06cc \u0634\u0648\u062f\u060c \u0648 \u0647\u06cc\u0686 \u062a\u0639\u0631\u06cc\u0641 \u0631\u0648\u0634\u0646\u06cc \u062f\u0631 \u0645\u0648\u0631\u062f \u0627\u06cc\u0646\u06a9\u0647 \u0648\u0627\u0642\u0639\u0627 \u0686\u06cc\u0633\u062a \u0648\u062c\u0648\u062f \u0646\u062f\u0627\u0631\u062f. <code>b<\/code> \u0627\u0633\u062a <em>\u062a\u0639\u0631\u06cc\u0641 \u0634\u062f\u0647 \u0627\u0633\u062a<\/em> \u0628\u0647 \u0639\u0646\u0648\u0627\u0646 \u06cc\u06a9 <em>\u0645\u0642\u062f\u0627\u0631 \u0635\u0641\u0631<\/em>.<\/p>\n<p>\u0686\u0647 <code>b<\/code> \u0645\u0633\u062a\u0642\u06cc\u0645\u0627\u064b \u0628\u0647 \u0639\u0646\u0648\u0627\u0646 \u062a\u0639\u0631\u06cc\u0641 \u0634\u062f <code>null<\/code> \u06cc\u0627 \u0628\u0647 \u0639\u0646\u0648\u0627\u0646 \u0645\u0642\u062f\u0627\u0631 \u0628\u0631\u06af\u0634\u062a\u06cc \u06cc\u06a9 \u062a\u0627\u0628\u0639 \u062a\u0639\u0631\u06cc\u0641 \u0645\u06cc \u0634\u0648\u062f (\u06a9\u0647 \u0641\u0642\u0637 a \u0631\u0627 \u0628\u0631\u0645\u06cc \u06af\u0631\u062f\u0627\u0646\u062f <code>null<\/code> \u0627\u0631\u0632\u0634) \u0645\u0647\u0645 \u0646\u06cc\u0633\u062a &#8211; \u0627\u06cc\u0646 \u0627\u0633\u062a <em>\u062a\u0639\u0631\u06cc\u0641 \u0634\u062f\u0647 \u0627\u0633\u062a<\/em> \u0645\u0627\u0646\u0646\u062f <em>\u0686\u06cc\u0632\u06cc<\/em>.<\/p>\n<p>\u0627\u0632 \u0633\u0648\u06cc \u062f\u06cc\u06af\u0631\u060c <code>a<\/code> \u06a9\u0627\u0645\u0644\u0627 \u0628\u0647 \u0645\u0639\u0646\u0627\u06cc \u0648\u0627\u0642\u0639\u06cc \u06a9\u0644\u0645\u0647 \u0627\u0633\u062a <em>\u0647\u06cc\u0686 \u0686\u06cc<\/em>.  \u0647\u06cc\u0686 \u062a\u06a9\u0644\u06cc\u0641\u06cc \u0627\u0646\u062c\u0627\u0645 \u0646\u0634\u062f \u0648 \u06a9\u0627\u0645\u0644\u0627\u064b \u0645\u0634\u062e\u0635 \u0646\u06cc\u0633\u062a \u06a9\u0647 \u0686\u0647 \u0686\u06cc\u0632\u06cc \u0628\u0627\u06cc\u062f \u0628\u0627\u0634\u062f \u06cc\u0627 \u0645\u06cc \u062a\u0648\u0627\u0646\u062f \u0628\u0627\u0634\u062f.<\/p>\n<p>\u062f\u0631 \u0639\u0645\u0644\u060c \u0628\u0633\u06cc\u0627\u0631\u06cc \u0627\u0632 <code>null<\/code> \u0648 <code>undefined<\/code> \u0645\u0642\u0627\u062f\u06cc\u0631 \u0627\u0632 \u062e\u0637\u0627\u06cc \u0627\u0646\u0633\u0627\u0646\u06cc \u062f\u0631 \u062d\u06cc\u0646 \u0628\u0631\u0646\u0627\u0645\u0647 \u0646\u0648\u06cc\u0633\u06cc \u0646\u0627\u0634\u06cc \u0645\u06cc \u0634\u0648\u0646\u062f \u0648 \u0627\u06cc\u0646 \u062f\u0648 \u062f\u0631 \u0628\u06cc\u0634\u062a\u0631 \u0645\u0648\u0627\u0631\u062f \u0628\u0627 \u0647\u0645 \u0647\u0633\u062a\u0646\u062f.  \u0647\u0646\u06af\u0627\u0645 \u0628\u0631\u0631\u0633\u06cc \u06cc\u06a9\u06cc &#8211; \u0645\u0627 \u0645\u0639\u0645\u0648\u0644\u0627\u064b \u062f\u06cc\u06af\u0631\u06cc \u0631\u0627 \u0646\u06cc\u0632 \u0628\u0631\u0631\u0633\u06cc \u0645\u06cc \u06a9\u0646\u06cc\u0645.<\/p>\n<h2 id=\"checkifvariableisundefinedornull\"><span class=\"ez-toc-section\" id=\"%d8%a8%d8%b1%d8%b1%d8%b3%db%8c_%da%a9%d9%86%db%8c%d8%af_%da%a9%d9%87_%d8%a2%db%8c%d8%a7_%d9%85%d8%aa%d8%ba%db%8c%d8%b1_%d8%a7%d8%b3%d8%aa_%db%8c%d8%a7_%d8%ae%db%8c%d8%b1_%d8%aa%d8%b9%d8%b1%db%8c%d9%81_%d9%86%d8%b4%d8%af%d9%87_%db%8c%d8%a7_%d8%ae%d8%a7%d9%84%db%8c\"><\/span>\u0628\u0631\u0631\u0633\u06cc \u06a9\u0646\u06cc\u062f \u06a9\u0647 \u0622\u06cc\u0627 \u0645\u062a\u063a\u06cc\u0631 \u0627\u0633\u062a \u06cc\u0627 \u062e\u06cc\u0631 <em>\u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647<\/em> \u06cc\u0627 <em>\u062e\u0627\u0644\u06cc<\/em><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u062f\u0648 \u0631\u0648\u06cc\u06a9\u0631\u062f \u0648\u062c\u0648\u062f \u062f\u0627\u0631\u062f \u06a9\u0647 \u0645\u06cc \u062a\u0648\u0627\u0646\u06cc\u062f \u0647\u0646\u06af\u0627\u0645 \u0628\u0631\u0631\u0633\u06cc \u0627\u06cc\u0646\u06a9\u0647 \u0622\u06cc\u0627 \u06cc\u06a9 \u0645\u062a\u063a\u06cc\u0631 \u0627\u0633\u062a \u06cc\u0627 \u062e\u06cc\u0631\u060c \u0627\u0646\u062a\u062e\u0627\u0628 \u06a9\u0646\u06cc\u062f <code>undefined<\/code> \u06cc\u0627 <code>null<\/code> \u062f\u0631 \u062c\u0627\u0648\u0627 \u0627\u0633\u06a9\u0631\u06cc\u067e\u062a \u0648\u0627\u0646\u06cc\u0644\u06cc<\/p>\n<h3 id=\"andoperators\"><span class=\"ez-toc-section\" id=\"_%d9%88_%d8%a7%d9%be%d8%b1%d8%a7%d8%aa%d9%88%d8%b1%d9%87%d8%a7\"><\/span>== \u0648 === \u0627\u067e\u0631\u0627\u062a\u0648\u0631\u0647\u0627<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u062a\u0641\u0627\u0648\u062a \u0648\u062c\u0648\u062f \u062f\u0627\u0631\u062f \u0628\u06cc\u0646 <strong><em>\u0627\u067e\u0631\u0627\u062a\u0648\u0631 \u0628\u0631\u0627\u0628\u0631\u06cc \u0633\u0633\u062a<\/em><\/strong>  (<code>==<\/code>) \u0648 <strong><em>\u0627\u067e\u0631\u0627\u062a\u0648\u0631 \u0628\u0631\u0627\u0628\u0631\u06cc \u062f\u0642\u06cc\u0642<\/em><\/strong>  (<code>===<\/code>) \u062f\u0631 \u062c\u0627\u0648\u0627 \u0627\u0633\u06a9\u0631\u06cc\u067e\u062a.  \u0627\u0632 \u062f\u0633\u062a \u062f\u0627\u062f\u0646 \u0628\u0631\u0627\u0628\u0631\u06cc <em>\u0645\u0645\u06a9\u0646 \u0627\u0633\u062a<\/em> \u0645\u0646\u062c\u0631 \u0628\u0647 \u0646\u062a\u0627\u06cc\u062c \u063a\u06cc\u0631\u0645\u0646\u062a\u0638\u0631\u0647 \u0645\u06cc \u0634\u0648\u062f \u0648 \u062f\u0631 \u0627\u06cc\u0646 \u0632\u0645\u06cc\u0646\u0647 \u0645\u062a\u0641\u0627\u0648\u062a \u0627\u0632 \u0639\u0645\u0644\u06af\u0631 \u0628\u0631\u0627\u0628\u0631\u06cc \u062f\u0642\u06cc\u0642 \u0631\u0641\u062a\u0627\u0631 \u0645\u06cc \u06a9\u0646\u062f:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-literal\">null<\/span> == <span class=\"hljs-literal\">undefined<\/span>);  <span class=\"hljs-comment\">\/\/ true<\/span>\n<span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-literal\">null<\/span> === <span class=\"hljs-literal\">undefined<\/span>); <span class=\"hljs-comment\">\/\/ false<\/span>\n<\/code><\/pre>\n<div class=\"alert alert-note\">\n<div class=\"flex\">\n<div class=\"flex-shrink-0 mr-3\"><\/div>\n<div class=\"w-full\">\n<p><strong>\u062a\u0648\u062c\u0647 \u062f\u0627\u0634\u062a\u0647 \u0628\u0627\u0634\u06cc\u062f:<\/strong> \u0627\u06cc\u0646 \u0631\u0627 \u0646\u0628\u0627\u06cc\u062f \u0628\u0647 \u0639\u0646\u0648\u0627\u0646 <em>\u0627\u062b\u0628\u0627\u062a<\/em> \u06a9\u0647 <code>null<\/code> \u0648 <code>undefined<\/code> \u0647\u0645\u0627\u0646 \u0647\u0633\u062a\u0646\u062f.  \u0627\u06cc\u0646 <em>\u0639\u0645\u0644\u06af\u0631 \u0628\u0631\u0627\u0628\u0631\u06cc \u0634\u0644<\/em> \u0627\u0632 \u062a\u0639\u0627\u0631\u06cc\u0641 &#8220;\u0645\u062d\u0627\u0648\u0631\u0647 \u0627\u06cc&#8221; \u0627\u0631\u0632\u0634 \u0647\u0627\u06cc \u0635\u062f\u0642\/\u06a9\u0627\u0630\u0628 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u0645\u06cc \u06a9\u0646\u062f. <code>0<\/code>\u060c <code>\"\"<\/code> \u0648 <code>()<\/code> \u0628\u0647 \u0639\u0646\u0648\u0627\u0646 \u0627\u0631\u0632\u06cc\u0627\u0628\u06cc \u0645\u06cc \u0634\u0648\u0646\u062f <code>false<\/code> \u0647\u0645\u0627\u0646\u0637\u0648\u0631 \u06a9\u0647 \u0622\u0646\u0647\u0627 \u06a9\u0645\u0628\u0648\u062f \u062f\u0627\u062f\u0647 \u0631\u0627 \u0646\u0634\u0627\u0646 \u0645\u06cc \u062f\u0647\u0646\u062f\u060c \u062d\u062a\u06cc \u0627\u06af\u0631 \u0622\u0646\u0647\u0627 \u062f\u0631 \u0648\u0627\u0642\u0639 \u0628\u0631\u0627\u0628\u0631 \u0628\u0627 \u06cc\u06a9 \u0628\u0648\u0644\u06cc \u0646\u06cc\u0633\u062a\u0646\u062f.<\/p>\n<\/p><\/div><\/div><\/div>\n<p>\u06a9\u0647 \u06af\u0641\u062a\u0647 \u0634\u062f &#8211; \u0627\u0632 \u0622\u0646\u062c\u0627\u06cc\u06cc \u06a9\u0647 \u0639\u0645\u0644\u06af\u0631 \u0628\u0631\u0627\u0628\u0631\u06cc \u0633\u0633\u062a \u0631\u0641\u062a\u0627\u0631 \u0645\u06cc \u06a9\u0646\u062f <code>null<\/code> \u0648 <code>undefined<\/code> \u0628\u0647 \u0639\u0646\u0648\u0627\u0646 \u06cc\u06a9\u0633\u0627\u0646 &#8211; \u0645\u06cc \u062a\u0648\u0627\u0646\u06cc\u062f \u0627\u0632 \u0622\u0646 \u0628\u0647 \u0639\u0646\u0648\u0627\u0646 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u06a9\u0646\u06cc\u062f <em>\u06a9\u0648\u062a\u0627\u0647 \u0646\u0648\u06cc\u0633\u06cc<\/em> \u0646\u0633\u062e\u0647 \u0628\u0631\u0631\u0633\u06cc \u0628\u0631\u0627\u06cc \u0647\u0631 \u062f\u0648:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-comment\">\/\/ Undefined variable<\/span>\n<span class=\"hljs-keyword\">let<\/span> a;\n\n<span class=\"hljs-keyword\">if<\/span> (a == <span class=\"hljs-literal\">null<\/span>) {\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'Null or undefined value!'<\/span>);\n} <span class=\"hljs-keyword\">else<\/span> {\n  <span class=\"hljs-built_in\">console<\/span>.log(a);\n}\n<\/code><\/pre>\n<p>\u0627\u06cc\u0646 \u0628\u0631\u0631\u0633\u06cc \u0645\u06cc \u06a9\u0646\u062f \u06a9\u0647 \u0622\u06cc\u0627 <code>a<\/code> \u0627\u0633\u062a <em>\u06cc\u0627 <code>null<\/code> \u06cc\u0627 <code>undefined<\/code><\/em>.  \u0627\u0632 \u0622\u0646\u062c\u0627 \u06a9\u0647 <code>a<\/code> \u0627\u0633\u062a <code>undefined<\/code>\u060c \u0627\u06cc\u0646 \u0646\u062a\u06cc\u062c\u0647 \u0645\u06cc \u0634\u0648\u062f:<\/p>\n<pre><code class=\"hljs\">Null or undefined value!\n<\/code><\/pre>\n<p>\u0627\u06af\u0631\u0686\u0647\u060c \u0645\u0627 \u0648\u0627\u0642\u0639\u0627\u064b \u0646\u0645\u06cc \u062f\u0627\u0646\u06cc\u0645 \u06a9\u062f\u0627\u0645 \u06cc\u06a9 \u0627\u0632 \u0627\u06cc\u0646 \u0645\u0648\u0627\u0631\u062f \u0627\u0633\u062a.  \u0627\u06af\u0631 \u0628\u062e\u0648\u0627\u0647\u06cc\u0645 \u0627\u0632 \u0639\u0645\u0644\u06af\u0631 \u0633\u062e\u062a \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u06a9\u0646\u06cc\u0645\u060c \u06a9\u0647 \u0627\u06af\u0631 \u0631\u0627 \u0628\u0631\u0631\u0633\u06cc \u0645\u06cc \u06a9\u0646\u062f <code>a<\/code> \u0627\u0633\u062a <code>null<\/code>\u060c \u0627\u06af\u0631 \u0628\u0627 \u06cc\u06a9 \u0645\u0648\u0627\u062c\u0647 \u0634\u0648\u06cc\u0645 \u0628\u0647 \u0637\u0631\u0632 \u0646\u0627\u062e\u0648\u0634\u0627\u06cc\u0646\u062f\u06cc \u0634\u06af\u0641\u062a \u0632\u062f\u0647 \u062e\u0648\u0627\u0647\u06cc\u0645 \u0634\u062f <code>undefined<\/code> \u0627\u0631\u0632\u0634 \u062f\u0631 <code>console.log()<\/code> \u0628\u06cc\u0627\u0646\u06cc\u0647:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-keyword\">let<\/span> a;\n\n<span class=\"hljs-keyword\">if<\/span> (a === <span class=\"hljs-literal\">null<\/span>) {\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'Null or undefined value!'<\/span>);\n} <span class=\"hljs-keyword\">else<\/span> {\n  <span class=\"hljs-built_in\">console<\/span>.log(a); <span class=\"hljs-comment\">\/\/ undefined<\/span>\n}\n<\/code><\/pre>\n<p><code>a<\/code>  \u0648\u0627\u0642\u0639\u0627 <em>\u0646\u06cc\u0633\u062a<\/em> <code>null<\/code>\u060c \u0627\u0645\u0627 \u0622\u0646 <em>\u0627\u0633\u062a<\/em> <code>undefined<\/code>.  \u062f\u0631 \u0627\u06cc\u0646 \u0645\u0648\u0631\u062f\u060c \u0645\u0627 \u0645\u06cc \u062e\u0648\u0627\u0647\u06cc\u0645 \u0622\u0646\u0647\u0627 \u0631\u0627 \u0628\u0647 \u0637\u0648\u0631 \u062c\u062f\u0627\u06af\u0627\u0646\u0647 \u0628\u0631\u0631\u0633\u06cc \u06a9\u0646\u06cc\u0645\u060c \u0627\u0645\u0627 \u0627\u0646\u0639\u0637\u0627\u0641 \u067e\u0630\u06cc\u0631\u06cc \u0644\u0627\u0632\u0645 \u0628\u0631\u0627\u06cc \u062f\u0627\u0646\u0633\u062a\u0646 \u062f\u0644\u06cc\u0644 \u0648\u0627\u0642\u0639\u06cc \u062c\u0631\u06cc\u0627\u0646 \u0631\u0627 \u062f\u0627\u0634\u062a\u0647 \u0628\u0627\u0634\u06cc\u0645:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-keyword\">let<\/span> a;\n\n<span class=\"hljs-keyword\">if<\/span> (a === <span class=\"hljs-literal\">null<\/span> || a === <span class=\"hljs-literal\">undefined<\/span>) { <span class=\"hljs-comment\">\/\/ true<\/span>\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'Null or undefined value!'<\/span>);\n} <span class=\"hljs-keyword\">else<\/span> {\n  <span class=\"hljs-built_in\">console<\/span>.log(a);\n}\n<\/code><\/pre>\n<p>\u062f\u0631 \u0627\u06cc\u0646\u062c\u0627\u060c \u0645\u0627 \u0622\u0646\u0647\u0627 \u0631\u0627 \u0628\u0627 \u06cc\u06a9 OR \u0627\u0646\u062d\u0635\u0627\u0631\u06cc \u062a\u0631\u06a9\u06cc\u0628 \u06a9\u0631\u062f\u0647\u200c\u0627\u06cc\u0645 &#8211; \u0627\u06af\u0631 \u0686\u0647 \u0627\u06af\u0631 \u0628\u062e\u0648\u0627\u0647\u06cc\u062f \u0645\u06cc\u200c\u062a\u0648\u0627\u0646\u06cc\u062f \u0622\u0646\u0647\u0627 \u0631\u0627 \u0628\u0631\u0627\u06cc \u0639\u0645\u0644\u06cc\u0627\u062a \u0628\u0627\u0632\u06cc\u0627\u0628\u06cc \u0645\u062e\u062a\u0644\u0641 \u0627\u0632 \u0647\u0645 \u062c\u062f\u0627 \u06a9\u0646\u06cc\u062f:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-keyword\">let<\/span> a;\n\n<span class=\"hljs-keyword\">if<\/span> (a === <span class=\"hljs-literal\">null<\/span>) {\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'Null value!'<\/span>);\n} <span class=\"hljs-keyword\">else<\/span> <span class=\"hljs-keyword\">if<\/span> (a === <span class=\"hljs-literal\">undefined<\/span>) { <span class=\"hljs-comment\">\/\/ true<\/span>\n  <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'Undefined value!'<\/span>);\n}\n<\/code><\/pre>\n<div class=\"alert alert-note\">\n<div class=\"flex\">\n<div class=\"flex-shrink-0 mr-3\"><\/div>\n<div class=\"w-full\">\n<p><strong>\u062a\u0648\u062c\u0647 \u062f\u0627\u0634\u062a\u0647 \u0628\u0627\u0634\u06cc\u062f:<\/strong> \u0634\u0627\u06cc\u0627\u0646 \u0630\u06a9\u0631 \u0627\u0633\u062a \u06a9\u0647 \u0627\u06af\u0631 \u0645\u0631\u062c\u0639 \u0648\u062c\u0648\u062f \u0646\u062f\u0627\u0634\u062a\u0647 \u0628\u0627\u0634\u062f\u060c \u0627\u0644\u0641 <code>ReferenceError<\/code> \u067e\u0631\u062a\u0627\u0628 \u062e\u0648\u0627\u0647\u062f \u0634\u062f.  \u0628\u0627 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u0627\u0632 \u0627\u06cc\u0646 \u0645\u06cc \u062a\u0648\u0627\u0646 \u0627\u0632 \u0627\u06cc\u0646 \u0627\u0645\u0631 \u062c\u0644\u0648\u06af\u06cc\u0631\u06cc \u06a9\u0631\u062f <code>typeof<\/code> \u0627\u067e\u0631\u0627\u062a\u0648\u0631\u060c \u0627\u06af\u0631\u0686\u0647 \u0645\u0645\u06a9\u0646 \u0627\u0633\u062a \u0627\u0632 \u0645\u0646\u0638\u0631 \u0637\u0631\u0627\u062d\u06cc \u06a9\u062f \u0628\u0647\u062a\u0631\u06cc\u0646 \u0627\u0646\u062a\u062e\u0627\u0628 \u0646\u0628\u0627\u0634\u062f.  \u0627\u06af\u0631 \u0627\u0632 a \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u0645\u06cc \u06a9\u0646\u06cc\u062f <em>\u0645\u0648\u062c\u0648\u062f \u0646\u06cc\u0633\u062a<\/em> \u0645\u062a\u063a\u06cc\u0631 \u0645\u0631\u062c\u0639 &#8211; \u0628\u06cc \u0633\u0631 \u0648 \u0635\u062f\u0627 \u0622\u0646 \u0645\u0633\u0626\u0644\u0647 \u0631\u0627 \u0628\u0627 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u0627\u0632 \u0622\u0646 \u0646\u0627\u062f\u06cc\u062f\u0647 \u0645\u06cc \u06af\u06cc\u0631\u062f <code>typeof<\/code> \u0645\u0645\u06a9\u0646 \u0627\u0633\u062a \u0645\u0646\u062c\u0631 \u0628\u0647 \u0634\u06a9\u0633\u062a \u0628\u06cc \u0633\u0631 \u0648 \u0635\u062f\u0627 \u0634\u0648\u062f.<\/p>\n<\/p><\/div><\/div><\/div>\n<h3 id=\"typeofoperator\"><span class=\"ez-toc-section\" id=\"%d9%86%d9%88%d8%b9_%d8%a7%d9%be%d8%b1%d8%a7%d8%aa%d9%88%d8%b1\"><\/span>\u0646\u0648\u0639 \u0627\u067e\u0631\u0627\u062a\u0648\u0631<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u0627\u06cc\u0646 <code>typeof<\/code> \u0627\u067e\u0631\u0627\u062a\u0648\u0631 \u0639\u0644\u0627\u0648\u0647 \u0628\u0631 \u0627\u06cc\u0646 \u0645\u06cc \u062a\u0648\u0627\u0646\u062f \u062f\u0631 \u06a9\u0646\u0627\u0631 <code>===<\/code> \u0639\u0645\u0644\u06af\u0631 \u0628\u0631\u0627\u06cc \u0628\u0631\u0631\u0633\u06cc \u0627\u06cc\u0646\u06a9\u0647 \u0622\u06cc\u0627 \u0646\u0648\u0639 \u06cc\u06a9 \u0645\u062a\u063a\u06cc\u0631 \u0628\u0631\u0627\u0628\u0631 \u0627\u0633\u062a \u06cc\u0627 \u062e\u06cc\u0631 <code>'undefined'<\/code> \u06cc\u0627 <code>'null'<\/code>:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-keyword\">let<\/span> a;\n\n<span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> a === <span class=\"hljs-string\">'undefined'<\/span>) {\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'Undefined variable'<\/span>);\n} <span class=\"hljs-keyword\">else<\/span> <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> a === <span class=\"hljs-string\">'null'<\/span>) {\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'Null-value'<\/span>);\n}\n<\/code><\/pre>\n<p>\u0627\u06cc\u0646 \u0646\u062a\u06cc\u062c\u0647 \u062f\u0631:<\/p>\n<pre><code class=\"hljs\">Undefined variable\n<\/code><\/pre>\n<p>\u0628\u0627 \u0627\u06cc\u0646 \u062d\u0627\u0644\u060c \u0634\u0627\u06cc\u0627\u0646 \u0630\u06a9\u0631 \u0627\u0633\u062a \u06a9\u0647 \u0627\u06af\u0631 \u0634\u0645\u0627 \u0631\u0627 \u062f\u0631 \u06cc\u06a9 <em>\u0645\u0648\u062c\u0648\u062f \u0646\u06cc\u0633\u062a<\/em> \u0645\u062a\u063a\u06cc\u0631 \u0645\u0631\u062c\u0639 &#8211; <code>typeof<\/code> \u062e\u0648\u0634\u062d\u0627\u0644 \u0627\u0633\u062a \u06a9\u0647 \u0628\u0627 \u0622\u0646 \u06a9\u0627\u0631 \u0645\u06cc \u06a9\u0646\u062f \u0648 \u0628\u0627 \u0622\u0646 \u0631\u0641\u062a\u0627\u0631 \u0645\u06cc \u06a9\u0646\u062f <code>undefined<\/code>:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> someVar === <span class=\"hljs-string\">'undefined'<\/span>) {\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'Undefined variable'<\/span>);\n} <span class=\"hljs-keyword\">else<\/span> <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> someVar === <span class=\"hljs-string\">'null'<\/span>) {\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'Null-value'<\/span>);\n}\n<\/code><\/pre>\n<p>\u0627\u06cc\u0646 \u06a9\u062f \u0647\u0645\u0686\u0646\u06cc\u0646 \u0646\u062a\u06cc\u062c\u0647 \u0645\u06cc \u062f\u0647\u062f:<\/p>\n<pre><code class=\"hljs\">Undefined variable\n<\/code><\/pre>\n<p>\u0627\u0632 \u0646\u0638\u0631 \u0641\u0646\u06cc\u060c <code>some_var<\/code> <em>\u0627\u0633\u062a<\/em> \u06cc\u06a9 \u0645\u062a\u063a\u06cc\u0631 \u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647\u060c \u0632\u06cc\u0631\u0627 \u0647\u06cc\u0686 \u062a\u062e\u0635\u06cc\u0635\u06cc \u0646\u062f\u0627\u0631\u062f.  \u0627\u0632 \u0633\u0648\u06cc \u062f\u06cc\u06af\u0631\u060c \u0627\u06cc\u0646 \u0645\u06cc \u062a\u0648\u0627\u0646\u062f <code>typeof<\/code> \u0628\u06cc \u0633\u0631 \u0648 \u0635\u062f\u0627 \u0634\u06a9\u0633\u062a \u0645\u06cc \u062e\u0648\u0631\u062f \u0648 \u0633\u06cc\u06af\u0646\u0627\u0644 \u0645\u06cc \u062f\u0647\u062f \u06a9\u0647 <em>\u0648\u0631\u0648\u062f\u06cc<\/em> \u0645\u0642\u062f\u0627\u0631 \u0645\u0645\u06a9\u0646 \u0627\u0633\u062a \u0645\u0634\u06a9\u0644 \u062f\u0627\u0634\u062a\u0647 \u0628\u0627\u0634\u062f\u060c \u0628\u0647 \u062c\u0627\u06cc \u0627\u06cc\u0646\u06a9\u0647 \u062e\u0637\u0627\u06cc\u06cc \u0627\u06cc\u062c\u0627\u062f \u06a9\u0646\u062f \u06a9\u0647 \u0645\u0634\u062e\u0635 \u0645\u06cc \u06a9\u0646\u062f \u0628\u0627 \u06cc\u06a9 \u0645\u062a\u063a\u06cc\u0631 \u063a\u06cc\u0631 \u0645\u0648\u062c\u0648\u062f \u0633\u0631\u0648\u06a9\u0627\u0631 \u062f\u0627\u0631\u06cc\u062f.<\/p>\n<p>\u0628\u0647 \u0639\u0646\u0648\u0627\u0646 \u0645\u062b\u0627\u0644 &#8211; \u062a\u0635\u0648\u0631 \u06a9\u0646\u06cc\u062f \u0627\u0634\u062a\u0628\u0627\u0647 \u062a\u0627\u06cc\u067e\u06cc \u06a9\u0631\u062f\u0647 \u0627\u06cc\u062f \u0648 \u0628\u0647 \u0637\u0648\u0631 \u062a\u0635\u0627\u062f\u0641\u06cc \u0648\u0627\u0631\u062f \u0634\u062f\u0647 \u0627\u06cc\u062f <code>somevariable<\/code> \u0628\u062c\u0627\u06cc <code>someVariable<\/code> \u062f\u0631 <code>if<\/code> \u0639\u0628\u0627\u0631\u062a:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-keyword\">let<\/span> someVariable = <span class=\"hljs-string\">'Hello!'<\/span>\n\n<span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> somevariable === <span class=\"hljs-string\">'undefined'<\/span>) {\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'Undefined variable'<\/span>);\n} <span class=\"hljs-keyword\">else<\/span> <span class=\"hljs-keyword\">if<\/span> (<span class=\"hljs-keyword\">typeof<\/span> somevariable === <span class=\"hljs-string\">'null'<\/span>) {\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'Null-value'<\/span>);\n} <span class=\"hljs-keyword\">else<\/span> {\n    <span class=\"hljs-built_in\">console<\/span>.log(somevariable);\n}\n<\/code><\/pre>\n<p>\u062f\u0631 \u0627\u06cc\u0646\u062c\u0627\u060c \u0645\u0627 \u0633\u0639\u06cc \u0645\u06cc \u06a9\u0646\u06cc\u0645 \u0628\u0631\u0631\u0633\u06cc \u06a9\u0646\u06cc\u0645 \u06a9\u0647 \u0622\u06cc\u0627 <code>someVariable<\/code> \u0627\u0633\u062a <code>null<\/code> \u06cc\u0627 <code>undefined<\/code>\u060c \u0648 \u0627\u06cc\u0646 \u0646\u06cc\u0633\u062a.  \u0628\u0627 \u0627\u06cc\u0646 \u062d\u0627\u0644\u060c \u0628\u0647 \u062f\u0644\u06cc\u0644 \u0627\u0634\u062a\u0628\u0627\u0647 \u062a\u0627\u06cc\u067e\u06cc\u060c <code>somevariable<\/code> \u062f\u0631 \u0639\u0648\u0636 \u0628\u0631\u0631\u0633\u06cc \u0645\u06cc \u0634\u0648\u062f \u0648 \u0646\u062a\u06cc\u062c\u0647 \u0627\u06cc\u0646 \u0627\u0633\u062a:<\/p>\n<pre><code class=\"hljs\">Undefined variable\n<\/code><\/pre>\n<p>\u062f\u0631 \u06cc\u06a9 \u0633\u0646\u0627\u0631\u06cc\u0648\u06cc \u067e\u06cc\u0686\u06cc\u062f\u0647 \u062a\u0631 &#8211; \u0645\u0645\u06a9\u0646 \u0627\u0633\u062a \u062a\u0634\u062e\u06cc\u0635 \u0627\u06cc\u0646 \u0627\u0634\u062a\u0628\u0627\u0647 \u062a\u0627\u06cc\u067e\u06cc \u0633\u062e\u062a \u062a\u0631 \u0627\u0632 \u0627\u06cc\u0646 \u0628\u0627\u0634\u062f.  \u0645\u0627 \u06cc\u06a9 \u0634\u06a9\u0633\u062a \u062e\u0627\u0645\u0648\u0634 \u062f\u0627\u0634\u062a\u0647 \u0627\u06cc\u0645 \u0648 \u0645\u0645\u06a9\u0646 \u0627\u0633\u062a \u0648\u0642\u062a \u0628\u06af\u0630\u0627\u0631\u06cc\u0645 \u0631\u0648\u06cc \u062f\u0646\u0628\u0627\u0644\u0647 \u0627\u06cc \u062f\u0631\u0648\u063a\u06cc\u0646  \u0627\u0632 \u0633\u0648\u06cc \u062f\u06cc\u06af\u0631\u060c \u0641\u0642\u0637 \u0628\u0627 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u0627\u0632 <code>==<\/code> \u0648 <code>===<\/code> \u0627\u067e\u0631\u0627\u062a\u0648\u0631\u0647\u0627\u06cc \u0627\u06cc\u0646\u062c\u0627 \u0628\u0647 \u0645\u0627 \u062f\u0631 \u0645\u0648\u0631\u062f \u0645\u062a\u063a\u06cc\u0631 \u0645\u0631\u062c\u0639 \u063a\u06cc\u0631 \u0645\u0648\u062c\u0648\u062f \u0647\u0634\u062f\u0627\u0631 \u062f\u0627\u062f\u0647 \u0628\u0648\u062f\u0646\u062f:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-keyword\">let<\/span> someVariable = <span class=\"hljs-string\">'Hello!'<\/span>\n\n<span class=\"hljs-keyword\">if<\/span> (somevariable === <span class=\"hljs-string\">'undefined'<\/span>) {\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'Undefined variable'<\/span>);\n} <span class=\"hljs-keyword\">else<\/span> <span class=\"hljs-keyword\">if<\/span> (somevariable === <span class=\"hljs-string\">'null'<\/span>) {\n    <span class=\"hljs-built_in\">console<\/span>.log(<span class=\"hljs-string\">'Null-value'<\/span>);\n} <span class=\"hljs-keyword\">else<\/span> {\n    <span class=\"hljs-built_in\">console<\/span>.log(somevariable);\n}\n<\/code><\/pre>\n<p>\u0627\u06cc\u0646 \u06a9\u062f \u0646\u062a\u06cc\u062c\u0647 \u0645\u06cc \u062f\u0647\u062f:<\/p>\n<pre><code class=\"hljs\">error: Uncaught ReferenceError: somevariable is not defined\n<\/code><\/pre>\n<div class=\"alert alert-note\">\n<div class=\"flex\">\n<div class=\"flex-shrink-0 mr-3\"><\/div>\n<div class=\"w-full\">\n<p><strong>\u062a\u0648\u062c\u0647 \u062f\u0627\u0634\u062a\u0647 \u0628\u0627\u0634\u06cc\u062f:<\/strong> \u0627\u06cc\u0646 \u0628\u0647 \u0627\u06cc\u0646 \u0645\u0639\u0646\u06cc \u0646\u06cc\u0633\u062a <code>typeof<\/code> \u0630\u0627\u062a\u0627\u064b \u0627\u0646\u062a\u062e\u0627\u0628 \u0628\u062f\u06cc \u0627\u0633\u062a &#8211; \u0627\u0645\u0627 \u0627\u06cc\u0646 \u0645\u0641\u0647\u0648\u0645 \u0631\u0627 \u0646\u06cc\u0632 \u0628\u0647 \u062f\u0646\u0628\u0627\u0644 \u062f\u0627\u0631\u062f.<\/p>\n<\/p><\/div><\/div><\/div>\n<h2 id=\"usinglodashtocheckifvariableisnullundefinedornil\"><span class=\"ez-toc-section\" id=\"%d8%a7%d8%b3%d8%aa%d9%81%d8%a7%d8%af%d9%87_%d8%a7%d8%b2_lodash_%d8%a8%d8%b1%d8%a7%db%8c_%d8%a8%d8%b1%d8%b1%d8%b3%db%8c_%d8%a7%db%8c%d9%86%da%a9%d9%87_%d8%a2%db%8c%d8%a7_%d9%85%d8%aa%d8%ba%db%8c%d8%b1_%d8%a7%d8%b3%d8%aa_%db%8c%d8%a7_%d8%ae%db%8c%d8%b1_%d8%ae%d8%a7%d9%84%db%8c%d8%8c_%d8%aa%d8%b9%d8%b1%db%8c%d9%81_%d9%86%d8%b4%d8%af%d9%87_%db%8c%d8%a7_%d8%b5%d9%81%d8%b1\"><\/span>\u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u0627\u0632 Lodash \u0628\u0631\u0627\u06cc \u0628\u0631\u0631\u0633\u06cc \u0627\u06cc\u0646\u06a9\u0647 \u0622\u06cc\u0627 \u0645\u062a\u063a\u06cc\u0631 \u0627\u0633\u062a \u06cc\u0627 \u062e\u06cc\u0631 <em>\u062e\u0627\u0644\u06cc<\/em>\u060c <em>\u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647<\/em> \u06cc\u0627 <em>\u0635\u0641\u0631<\/em><span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u062f\u0631 \u0646\u0647\u0627\u06cc\u062a &#8211; \u0645\u06cc \u062a\u0648\u0627\u0646\u06cc\u062f \u06a9\u062a\u0627\u0628\u062e\u0627\u0646\u0647 \u0647\u0627\u06cc \u062e\u0627\u0631\u062c\u06cc \u0631\u0627 \u0639\u0644\u0627\u0648\u0647 \u0628\u0631 \u0627\u067e\u0631\u0627\u062a\u0648\u0631\u0647\u0627\u06cc \u062f\u0627\u062e\u0644\u06cc \u0627\u0646\u062a\u062e\u0627\u0628 \u06a9\u0646\u06cc\u062f.  \u062f\u0631 \u062d\u0627\u0644\u06cc \u06a9\u0647 \u0648\u0627\u0631\u062f \u06a9\u0631\u062f\u0646 \u06cc\u06a9 \u06a9\u062a\u0627\u0628\u062e\u0627\u0646\u0647 \u062e\u0627\u0631\u062c\u06cc \u0645\u0648\u062c\u0647 \u0646\u06cc\u0633\u062a <em>\u0641\u0642\u0637<\/em> \u0628\u0631\u0627\u06cc \u0627\u0646\u062c\u0627\u0645 \u0627\u06cc\u0646 \u0628\u0631\u0631\u0633\u06cc &#8211; \u062f\u0631 \u0627\u06cc\u0646 \u0635\u0648\u0631\u062a\u060c \u0628\u0647\u062a\u0631 \u0627\u0633\u062a \u0641\u0642\u0637 \u0627\u0632 \u0627\u067e\u0631\u0627\u062a\u0648\u0631\u0647\u0627 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u06a9\u0646\u06cc\u062f.<\/p>\n<p>\u0628\u0627 \u0627\u06cc\u0646 \u062d\u0627\u0644\u060c Lodash \u062f\u0631 \u062d\u0627\u0644 \u062d\u0627\u0636\u0631 \u062f\u0631 \u0628\u0633\u06cc\u0627\u0631\u06cc \u0627\u0632 \u067e\u0631\u0648\u0698\u0647 \u0647\u0627 \u062d\u0636\u0648\u0631 \u062f\u0627\u0631\u062f &#8211; \u0627\u06cc\u0646 \u06cc\u06a9 \u06a9\u062a\u0627\u0628\u062e\u0627\u0646\u0647 \u067e\u0631 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u0627\u0633\u062a\u060c \u0648 \u0632\u0645\u0627\u0646\u06cc \u06a9\u0647 \u062f\u0631 \u062d\u0627\u0644 \u062d\u0627\u0636\u0631 \u0648\u062c\u0648\u062f \u062f\u0627\u0634\u062a\u0647 \u0628\u0627\u0634\u062f\u060c \u0628\u0627 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u0627\u0632 \u0686\u0646\u062f \u0631\u0648\u0634\u06cc \u06a9\u0647 \u0627\u0631\u0627\u0626\u0647 \u0645\u06cc \u062f\u0647\u062f\u060c \u06a9\u0627\u0631\u0627\u06cc\u06cc \u06a9\u0627\u0647\u0634 \u0646\u0645\u06cc \u06cc\u0627\u0628\u062f.  \u0645\u0647\u0645\u062a\u0631 \u0627\u0632 \u0647\u0645\u0647\u060c Lodash \u0686\u0646\u062f\u06cc\u0646 \u0631\u0648\u0634 \u0645\u0641\u06cc\u062f \u0627\u0631\u0627\u0626\u0647 \u0645\u06cc \u062f\u0647\u062f \u06a9\u0647 \u0628\u0631\u0631\u0633\u06cc \u0645\u06cc \u06a9\u0646\u062f \u06a9\u0647 \u0622\u06cc\u0627 \u06cc\u06a9 \u0645\u062a\u063a\u06cc\u0631 \u0648\u062c\u0648\u062f \u062f\u0627\u0631\u062f \u06cc\u0627 \u062e\u06cc\u0631 <em>\u062e\u0627\u0644\u06cc<\/em>\u060c <em>\u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647<\/em> \u06cc\u0627 <em>\u0635\u0641\u0631<\/em>.<\/p>\n<h3 id=\"installandimportlodash\"><span class=\"ez-toc-section\" id=\"lodash_%d8%b1%d8%a7_%d9%86%d8%b5%d8%a8_%d9%88_%d9%88%d8%a7%d8%b1%d8%af_%da%a9%d9%86%db%8c%d8%af\"><\/span>Lodash \u0631\u0627 \u0646\u0635\u0628 \u0648 \u0648\u0627\u0631\u062f \u06a9\u0646\u06cc\u062f<span class=\"ez-toc-section-end\"><\/span><\/h3>\n<p>\u062a\u0648 \u0645\u06cc \u062a\u0648\u0627\u0646\u06cc import Lodash \u0627\u0632 \u0637\u0631\u06cc\u0642 CDN:<\/p>\n<pre><code class=\"hljs\">https:\/\/cdn.jsdelivr.net\/npm\/(email\u00a0protected)\/lodash.min.js\n<\/code><\/pre>\n<p>\u0622\u0646 \u0631\u0627 \u0628\u0647 \u0635\u0648\u0631\u062a \u0645\u062d\u0644\u06cc \u0627\u0632 a \u0648\u0627\u0631\u062f \u06a9\u0646\u06cc\u062f <code>.js<\/code> \u0641\u0627\u06cc\u0644:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-tag\">&lt;<span class=\"hljs-name\">script<\/span> <span class=\"hljs-attr\">src<\/span>=<span class=\"hljs-string\">\"lodash.js\"<\/span>&gt;<\/span><span class=\"hljs-tag\">&lt;\/<span class=\"hljs-name\">script<\/span>&gt;<\/span>\n<\/code><\/pre>\n<p>\u06cc\u0627 \u0627\u0632 \u0637\u0631\u06cc\u0642 NPM \u0646\u0635\u0628 \u06a9\u0646\u06cc\u062f:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-meta\">$<\/span><span class=\"bash\"> npm install lodash<\/span>\n<\/code><\/pre>\n<p>\u0639\u0644\u0627\u0648\u0647 \u0628\u0631 \u0627\u06cc\u0646\u060c \u0645\u06cc \u062a\u0648\u0627\u0646 \u0622\u0646 \u0631\u0627 \u0628\u0647 \u0639\u0646\u0648\u0627\u0646 \u06cc\u06a9 \u0645\u0627\u0698\u0648\u0644 ES6 \u0648\u0627\u0631\u062f \u06a9\u0631\u062f \u06cc\u0627 \u0627\u0632 \u0637\u0631\u06cc\u0642 \u0622\u0646 \u0648\u0627\u0631\u062f \u06a9\u0631\u062f <code>require()<\/code> \u0646\u062d\u0648:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-keyword\">import<\/span> _ <span class=\"hljs-keyword\">from<\/span> <span class=\"hljs-string\">'lodash'<\/span>;\n<span class=\"hljs-comment\">\/\/ OR<\/span>\n<span class=\"hljs-keyword\">const<\/span> _ = <span class=\"hljs-built_in\">require<\/span>(<span class=\"hljs-string\">'lodash'<\/span>);\n<\/code><\/pre>\n<div class=\"alert alert-note\">\n<div class=\"flex\">\n<div class=\"flex-shrink-0 mr-3\"><\/div>\n<div class=\"w-full\">\n<p><strong>\u062a\u0648\u062c\u0647 \u062f\u0627\u0634\u062a\u0647 \u0628\u0627\u0634\u06cc\u062f:<\/strong> \u0646\u0627\u0645\u06af\u0630\u0627\u0631\u06cc \u0646\u0645\u0648\u0646\u0647 Lodash \u06cc\u06a9 \u0642\u0631\u0627\u0631\u062f\u0627\u062f \u0627\u0633\u062a <code>_<\/code>\u060c \u0628\u0627 \u0646\u0627\u0645 \u0636\u0645\u0646\u06cc\u060c \u0644\u0627\u0632\u0645 \u0646\u06cc\u0633\u062a.<\/p>\n<\/p><\/div><\/div><\/div>\n<p>\u0627\u06a9\u0646\u0648\u0646 \u0645\u06cc\u200c\u062a\u0648\u0627\u0646\u06cc\u0645 \u0627\u0632 \u06a9\u062a\u0627\u0628\u062e\u0627\u0646\u0647 \u0628\u0631\u0627\u06cc \u0628\u0631\u0631\u0633\u06cc \u0627\u06cc\u0646\u06a9\u0647 \u0622\u06cc\u0627 \u06cc\u06a9 \u0645\u062a\u063a\u06cc\u0631 \u0648\u062c\u0648\u062f \u062f\u0627\u0631\u062f \u06cc\u0627 \u062e\u06cc\u0631 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u06a9\u0646\u06cc\u0645 <code>null<\/code>\u060c <code>undefined<\/code> \u06cc\u0627 <em>\u0635\u0641\u0631<\/em> &#8211; \u062c\u0627\u06cc\u06cc \u06a9\u0647 <em>\u0635\u0641\u0631<\/em> \u0627\u0634\u0627\u0631\u0647 \u0628\u0647 \u0647\u0631 \u062f\u0648 \u0645\u0635\u06cc\u0628\u062a \u0642\u0628\u0644\u06cc \u0627\u0633\u062a.  \u0645\u06cc \u062a\u0648\u0627\u0646 \u0627\u0632 \u0622\u0646 \u0628\u0647 \u0639\u0646\u0648\u0627\u0646 \u0646\u0633\u062e\u0647 \u0645\u062e\u062a\u0635\u0631 \u0628\u0631\u0627\u06cc \u0628\u0631\u0631\u0633\u06cc \u0647\u0631 \u062f\u0648 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u06a9\u0631\u062f:<\/p>\n<pre><code class=\"hljs\"><span class=\"hljs-keyword\">let<\/span> a = <span class=\"hljs-literal\">null<\/span>;\n\n<span class=\"hljs-built_in\">console<\/span>.log(_.isNull(a));       <span class=\"hljs-comment\">\/\/ true<\/span>\n<span class=\"hljs-built_in\">console<\/span>.log(_.isUndefined(a));  <span class=\"hljs-comment\">\/\/ false<\/span>\n<span class=\"hljs-built_in\">console<\/span>.log(_.isNil(a));        <span class=\"hljs-comment\">\/\/ true<\/span>\n<\/code><\/pre>\n<h2 id=\"conclusion\"><span class=\"ez-toc-section\" id=\"%d9%86%d8%aa%db%8c%d8%ac%d9%87\"><\/span>\u0646\u062a\u06cc\u062c\u0647<span class=\"ez-toc-section-end\"><\/span><\/h2>\n<p>\u062f\u0631 \u0627\u06cc\u0646 \u0631\u0627\u0647\u0646\u0645\u0627\u06cc \u06a9\u0648\u062a\u0627\u0647\u060c \u0645\u0627 \u0646\u06af\u0627\u0647\u06cc \u0628\u0647 \u0631\u0648\u0634 \u0628\u0631\u0631\u0633\u06cc \u0627\u06cc\u0646\u06a9\u0647 \u0622\u06cc\u0627 \u06cc\u06a9 \u0645\u062a\u063a\u06cc\u0631 \u062a\u0647\u06cc\u060c \u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647 \u06cc\u0627 <em>\u0635\u0641\u0631<\/em> \u062f\u0631 \u062c\u0627\u0648\u0627 \u0627\u0633\u06a9\u0631\u06cc\u067e\u062a \u0628\u0627 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u0627\u0632 <code>==<\/code>\u060c <code>===<\/code> \u0648 <code>typeof<\/code> \u0627\u067e\u0631\u0627\u062a\u0648\u0631\u0647\u0627\u060c \u0628\u0647 \u0645\u0632\u0627\u06cc\u0627 \u0648 \u0645\u0639\u0627\u06cc\u0628 \u0647\u0631 \u0631\u0648\u06cc\u06a9\u0631\u062f \u0627\u0634\u0627\u0631\u0647 \u0645\u06cc \u06a9\u0646\u0646\u062f.  \u062f\u0631 \u0646\u0647\u0627\u06cc\u062a\u060c \u0645\u0627 \u0646\u06af\u0627\u0647\u06cc \u06af\u0630\u0631\u0627 \u0628\u0647 \u0627\u0633\u062a\u0641\u0627\u062f\u0647 \u0627\u0632 Lodash \u0627\u0646\u062f\u0627\u062e\u062a\u0647\u200c\u0627\u06cc\u0645 &#8211; \u06cc\u06a9 \u06a9\u062a\u0627\u0628\u062e\u0627\u0646\u0647 \u0627\u0628\u0632\u0627\u0631\u06cc \u0645\u062d\u0628\u0648\u0628 \u0628\u0631\u0627\u06cc \u0627\u0646\u062c\u0627\u0645 \u0647\u0645\u0627\u0646 \u0628\u0631\u0631\u0633\u06cc\u200c\u0647\u0627.<\/p>\n<\/div>\n<p><br \/>\n<br \/>\u0645\u0646\u062a\u0634\u0631 \u0634\u062f\u0647 \u062f\u0631 1403-01-14 07:19:03<br \/>\n<\/p>\n\n\n<div class=\"kk-star-ratings kksr-auto kksr-align-center kksr-valign-bottom\"\n    data-payload='{&quot;align&quot;:&quot;center&quot;,&quot;id&quot;:&quot;15583&quot;,&quot;slug&quot;:&quot;default&quot;,&quot;valign&quot;:&quot;bottom&quot;,&quot;ignore&quot;:&quot;&quot;,&quot;reference&quot;:&quot;auto&quot;,&quot;class&quot;:&quot;&quot;,&quot;count&quot;:&quot;0&quot;,&quot;legendonly&quot;:&quot;&quot;,&quot;readonly&quot;:&quot;&quot;,&quot;score&quot;:&quot;0&quot;,&quot;starsonly&quot;:&quot;&quot;,&quot;best&quot;:&quot;5&quot;,&quot;gap&quot;:&quot;5&quot;,&quot;greet&quot;:&quot;\u0627\u0645\u062a\u06cc\u0627\u0632 \u0634\u0645\u0627 \u0628\u0647 \u0627\u06cc\u0646 \u0645\u0637\u0644\u0628&quot;,&quot;legend&quot;:&quot;0\\\/5 (0 \u0631\u0627\u06cc)&quot;,&quot;size&quot;:&quot;30&quot;,&quot;title&quot;:&quot;\u062c\u0627\u0648\u0627 \u0627\u0633\u06a9\u0631\u06cc\u067e\u062a: \u0628\u0631\u0631\u0633\u06cc \u06a9\u0646\u06cc\u062f \u06a9\u0647 \u0622\u06cc\u0627 \u0645\u062a\u063a\u06cc\u0631 \u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647 \u06cc\u0627 \u062a\u0647\u06cc \u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647 \u0627\u0633\u062a \u0648 \u0645\u0642\u0627\u062f\u06cc\u0631 \u062a\u0647\u06cc \u0647\u0645\u06cc\u0634\u0647 \u0628\u0647 \u0635\u0648\u0631\u062a \u0645\u062e\u0641\u06cc\u0627\u0646\u0647 \u0648\u0627\u0631\u062f \u062c\u0631\u06cc\u0627\u0646 \u06a9\u062f \u0645\u06cc \u0634\u0648\u0646\u062f.  \u0686\u0647 \u0645\u0627 \u06cc\u06a9 \u0645\u0631\u062c\u0639 \u0631\u0627 \u0627\u0632 \u0637\u0631\u06cc\u0642 \u0639\u0648\u0627\u0631\u0636 \u062c\u0627\u0646\u0628\u06cc \u0627\u0632 \u062f\u0633\u062a \u062f\u0647\u06cc\u0645\u060c \u0641\u0631\u0627\u0645\u0648\u0634 \u06a9\u0646\u06cc\u0645 \u06cc\u06a9 \u0645\u062a\u063a\u06cc\u0631 \u0645\u0631\u062c\u0639 \u0631\u0627 \u0628\u0647 \u06cc\u06a9 \u0634\u06cc \u062f\u0631 \u062d\u0627\u0641\u0638\u0647 \u0627\u062e\u062a\u0635\u0627\u0635 \u062f\u0647\u06cc\u0645\u060c \u06cc\u0627 \u06cc\u06a9 \u067e\u0627\u0633\u062e \u062e\u0627\u0644\u06cc \u0627\u0632 \u06cc\u06a9 \u0645\u0646\u0628\u0639\u060c \u067e\u0627\u06cc\u06af\u0627\u0647 \u062f\u0627\u062f\u0647 \u06cc\u0627 API \u062f\u06cc\u06af\u0631 \u062f\u0631\u06cc\u0627\u0641\u062a \u06a9\u0646\u06cc\u0645 - \u0628\u0627\u06cc\u062f \u0628\u0627 \u0645\u0648\u0627\u0631\u062f \u062a\u0639\u0631\u06cc\u0641 \u0646\u0634\u062f\u0647 \u0645\u0642\u0627\u0628\u0644\u0647 \u06a9\u0646\u06cc\u0645...&quot;,&quot;width&quot;:&quot;0&quot;,&quot;_legend&quot;:&quot;{score}\\\/{best} ({count} \u0631\u0627\u06cc)&quot;,&quot;font_factor&quot;:&quot;1.25&quot;}'>\n            \n<div class=\"kksr-stars\">\n    \n<div class=\"kksr-stars-inactive\">\n            <div class=\"kksr-star\" data-star=\"1\" style=\"padding-left: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 30px; height: 30px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"2\" style=\"padding-left: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 30px; height: 30px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"3\" style=\"padding-left: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 30px; height: 30px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"4\" style=\"padding-left: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 30px; height: 30px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" data-star=\"5\" style=\"padding-left: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 30px; height: 30px;\"><\/div>\n        <\/div>\n    <\/div>\n    \n<div class=\"kksr-stars-active\" style=\"width: 0px;\">\n            <div class=\"kksr-star\" style=\"padding-left: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 30px; height: 30px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-left: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 30px; height: 30px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-left: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 30px; height: 30px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-left: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 30px; height: 30px;\"><\/div>\n        <\/div>\n            <div class=\"kksr-star\" style=\"padding-left: 5px\">\n            \n\n<div class=\"kksr-icon\" style=\"width: 30px; height: 30px;\"><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n                \n\n<div class=\"kksr-legend\" style=\"font-size: 24px;\">\n            <span class=\"kksr-muted\">\u0627\u0645\u062a\u06cc\u0627\u0632 \u0634\u0645\u0627 \u0628\u0647 \u0627\u06cc\u0646 \u0645\u0637\u0644\u0628<\/span>\n    <\/div>\n    <\/div>\n","protected":false},"excerpt":{"rendered":"<p><span class=\"span-reading-time rt-reading-time\" style=\"display: block;\"><span class=\"rt-label rt-prefix\">\u0632\u0645\u0627\u0646 \u0644\u0627\u0632\u0645 \u0628\u0631\u0627\u06cc \u0645\u0637\u0627\u0644\u0639\u0647: <\/span> <span class=\"rt-time\"> 5<\/span> <span class=\"rt-label rt-postfix\">\u062f\u0642\u06cc\u0642\u0647<\/span><\/span>\u0645\u0639\u0631\u0641\u06cc undefined \u0648 null \u0645\u0642\u0627\u062f\u06cc\u0631 \u0647\u0645\u06cc\u0634\u0647 \u0628\u0647 \u0635\u0648\u0631\u062a \u0645\u062e\u0641\u06cc\u0627\u0646\u0647 \u0648\u0627\u0631\u062f \u062c\u0631\u06cc\u0627\u0646 \u06a9\u062f \u0645\u06cc \u0634\u0648\u0646\u062f. \u0686\u0647 \u0645\u0627 \u06cc\u06a9 \u0645\u0631\u062c\u0639 \u0631\u0627 \u0627\u0632 \u0637\u0631\u06cc\u0642 \u0639\u0648\u0627\u0631\u0636 \u062c\u0627\u0646\u0628\u06cc \u0627\u0632 \u062f\u0633\u062a \u062f\u0647\u06cc\u0645\u060c \u0641\u0631\u0627\u0645\u0648\u0634 \u06a9\u0646\u06cc\u0645 \u06cc\u06a9 \u0645\u062a\u063a\u06cc\u0631 \u0645\u0631\u062c\u0639 \u0631\u0627 \u0628\u0647 \u06cc\u06a9 \u0634\u06cc \u062f\u0631 \u062d\u0627\u0641\u0638\u0647 \u0627\u062e\u062a\u0635\u0627\u0635 \u062f\u0647\u06cc\u0645\u060c \u06cc\u0627 \u06cc\u06a9 \u067e\u0627\u0633\u062e \u062e\u0627\u0644\u06cc \u0627\u0632 \u06cc\u06a9 \u0645\u0646\u0628\u0639\u060c \u067e\u0627\u06cc\u06af\u0627\u0647 \u062f\u0627\u062f\u0647 \u06cc\u0627 API \u062f\u06cc\u06af\u0631 \u062f\u0631\u06cc\u0627\u0641\u062a \u06a9\u0646\u06cc\u0645 &#8211; \u0628\u0627\u06cc\u062f [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":9056,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1772,620],"tags":[1209,1843,1964,1938,2341,2147,4084,1776,1811,1781,1779,1800,1970,1965,1807,3690,1984,2846,4078,4082,1780,1103,4080,1961,2370,3032,1796,2750,1774,3715,3452,3555,1803,2437,2445,3515,2145,4081,4083,2552,1806,1788,1795,1969,2326,4079,3916,4085,2325,1953,1960,1790,2847,2322,2250,2273,2442,1831,1813],"class_list":["post-15583","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-javascript","category-programming","tag-api","tag-nodejs-hosting","tag----frontend","tag-1938","tag-2341","tag-2147","tag-4084","tag-1776","tag-1811","tag-1781","tag-1779","tag-1800","tag-1970","tag-1965","tag-1807","tag-3690","tag-1984","tag-2846","tag-4078","tag-4082","tag-1780","tag-1103","tag-4080","tag-1961","tag-2370","tag-3032","tag-1796","tag-2750","tag-1774","tag-3715","tag-3452","tag-3555","tag-1803","tag-2437","tag-2445","tag-3515","tag-2145","tag-4081","tag-4083","tag-2552","tag-1806","tag-1788","tag-1795","tag-1969","tag-2326","tag-4079","tag-3916","tag-4085","tag-2325","tag-1953","tag-1960","tag-1790","tag-2847","tag-2322","tag--nodejs","tag-2273","tag-2442","tag-1831","tag-1813"],"acf":[],"_links":{"self":[{"href":"https:\/\/rasanegaar.com\/blog\/wp-json\/wp\/v2\/posts\/15583","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rasanegaar.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rasanegaar.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rasanegaar.com\/blog\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/rasanegaar.com\/blog\/wp-json\/wp\/v2\/comments?post=15583"}],"version-history":[{"count":0,"href":"https:\/\/rasanegaar.com\/blog\/wp-json\/wp\/v2\/posts\/15583\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/rasanegaar.com\/blog\/wp-json\/wp\/v2\/media\/9056"}],"wp:attachment":[{"href":"https:\/\/rasanegaar.com\/blog\/wp-json\/wp\/v2\/media?parent=15583"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rasanegaar.com\/blog\/wp-json\/wp\/v2\/categories?post=15583"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rasanegaar.com\/blog\/wp-json\/wp\/v2\/tags?post=15583"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}