{"id":7425,"date":"2025-10-15T18:14:05","date_gmt":"2025-10-15T23:14:05","guid":{"rendered":"https:\/\/frontendmasters.com\/blog\/?p=7425"},"modified":"2025-10-15T18:14:34","modified_gmt":"2025-10-15T23:14:34","slug":"why-javascript-variables-dont-always-update","status":"publish","type":"post","link":"https:\/\/frontendmasters.com\/blog\/why-javascript-variables-dont-always-update\/","title":{"rendered":"Why JavaScript variables don&#8217;t always update"},"content":{"rendered":"\n<p>I liked <a href=\"https:\/\/cassidoo.co\/post\/js-pass-by-what\/\">this bit of JavaScript trivia<\/a> from Cassidy Williams.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p>Look at this JavaScript code:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-1\" data-shcb-language-name=\"JavaScript\" data-shcb-language-slug=\"javascript\"><span><code class=\"hljs language-javascript\"><span class=\"hljs-keyword\">let<\/span> &#91;CLOSED, OPEN] = &#91;{}, {}];\nCLOSED = {\n  <span class=\"hljs-attr\">cake<\/span>: OPEN,\n};\nOPEN = {\n  <span class=\"hljs-attr\">fish<\/span>: <span class=\"hljs-number\">5<\/span>,\n};\n<span class=\"hljs-built_in\">console<\/span>.log(CLOSED); <span class=\"hljs-comment\">\/\/ cake is {}<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-1\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">JavaScript<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">javascript<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Why is it that&nbsp;<code>CLOSED<\/code>&nbsp;is not&nbsp;<code>{ cake: { fish: 5 }}<\/code>?<\/p>\n<\/blockquote>\n\n\n\n<p>There is a clear answer, and it&#8217;s something worth making sure you understand before heading into a job interview that involves JavaScript.  <\/p>\n","protected":false},"excerpt":{"rendered":"<p>I liked this bit of JavaScript trivia from Cassidy Williams. There is a clear answer, and it&#8217;s something worth making sure you understand before heading into a job interview that involves JavaScript.<\/p>\n","protected":false},"author":1,"featured_media":7427,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"sig_custom_text":"","sig_image_type":"featured-image","sig_custom_image":0,"sig_is_disabled":false,"inline_featured_image":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[29],"tags":[3,22],"class_list":["post-7425","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-the-beat","tag-javascript","tag-job-hunting"],"acf":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/frontendmasters.com\/blog\/wp-content\/uploads\/2025\/10\/pexels-photo-6755092.jpeg?fit=1880%2C1253&ssl=1","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/frontendmasters.com\/blog\/wp-json\/wp\/v2\/posts\/7425","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/frontendmasters.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/frontendmasters.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/frontendmasters.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/frontendmasters.com\/blog\/wp-json\/wp\/v2\/comments?post=7425"}],"version-history":[{"count":2,"href":"https:\/\/frontendmasters.com\/blog\/wp-json\/wp\/v2\/posts\/7425\/revisions"}],"predecessor-version":[{"id":7428,"href":"https:\/\/frontendmasters.com\/blog\/wp-json\/wp\/v2\/posts\/7425\/revisions\/7428"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/frontendmasters.com\/blog\/wp-json\/wp\/v2\/media\/7427"}],"wp:attachment":[{"href":"https:\/\/frontendmasters.com\/blog\/wp-json\/wp\/v2\/media?parent=7425"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/frontendmasters.com\/blog\/wp-json\/wp\/v2\/categories?post=7425"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/frontendmasters.com\/blog\/wp-json\/wp\/v2\/tags?post=7425"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}