{"id":504,"date":"2025-12-05T14:52:35","date_gmt":"2025-12-05T06:52:35","guid":{"rendered":"https:\/\/www.52runoob.com\/?p=504"},"modified":"2025-12-05T14:52:35","modified_gmt":"2025-12-05T06:52:35","slug":"%e9%92%88%e5%af%b9%e5%88%9d%e5%ad%a6%e8%80%85%e7%9a%84javascript%e5%85%ab%e7%a7%8d%e7%b1%bb%e5%9e%8b%e5%ae%9e%e7%94%a8%e5%b0%8f%e6%8a%80%e5%b7%a7%e6%80%bb%e7%bb%93","status":"publish","type":"post","link":"https:\/\/www.52runoob.com\/index.php\/2025\/12\/05\/%e9%92%88%e5%af%b9%e5%88%9d%e5%ad%a6%e8%80%85%e7%9a%84javascript%e5%85%ab%e7%a7%8d%e7%b1%bb%e5%9e%8b%e5%ae%9e%e7%94%a8%e5%b0%8f%e6%8a%80%e5%b7%a7%e6%80%bb%e7%bb%93\/","title":{"rendered":"\u9488\u5bf9\u521d\u5b66\u8005\u7684JavaScript\u516b\u79cd\u7c7b\u578b\u5b9e\u7528\u5c0f\u6280\u5de7\u603b\u7ed3"},"content":{"rendered":"\n<p>\u4e0b\u9762\u7ed9\u4f60\u6574\u7406\u4e00\u4efd <strong>\u9488\u5bf9\u521d\u5b66\u8005\u7684 JavaScript \u516b\u79cd\u7c7b\u578b\u5b9e\u7528\u5c0f\u6280\u5de7\u603b\u7ed3<\/strong>\uff0c\u4ece\u57fa\u7840\u6570\u636e\u7c7b\u578b\u5230\u5f15\u7528\u7c7b\u578b\uff0c\u9644\u5e26\u6613\u61c2\u793a\u4f8b\u548c\u5b9e\u7528\u6280\u5de7\uff0c\u8ba9\u4f60\u5bf9 JS \u7c7b\u578b\u7406\u89e3\u66f4\u900f\u5f7b\u3002<\/p>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">1\ufe0f\u20e3 \u516b\u79cd\u57fa\u672c\u7c7b\u578b\u6982\u89c8<\/h1>\n\n\n\n<p>\u5728 JavaScript \u4e2d\uff0c<strong>\u516b\u79cd\u7c7b\u578b<\/strong>\u53ef\u4ee5\u5206\u4e3a\u4e24\u7c7b\uff1a<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u57fa\u672c\u7c7b\u578b\uff08Primitive Type\uff09<\/strong>\uff1a<code>Number<\/code>\u3001<code>String<\/code>\u3001<code>Boolean<\/code>\u3001<code>Symbol<\/code>\u3001<code>BigInt<\/code>\u3001<code>undefined<\/code>\u3001<code>null<\/code><\/li>\n\n\n\n<li><strong>\u5f15\u7528\u7c7b\u578b\uff08Reference Type\uff09<\/strong>\uff1a<code>Object<\/code>\uff08\u6570\u7ec4\u3001\u51fd\u6570\u3001\u5bf9\u8c61\u7b49\u90fd\u5c5e\u4e8e Object\uff09<\/li>\n<\/ol>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">2\ufe0f\u20e3 Number\uff08\u6570\u5b57\u7c7b\u578b\uff09<\/h1>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nconst num = 42;\nconst floatNum = 3.14;\n\n<\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u5c0f\u6280\u5de7\uff1a<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u68c0\u67e5 NaN\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nNumber.isNaN(0\/0) \/\/ true\n\n<\/pre><\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>\u5b89\u5168\u6574\u6570\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nNumber.MAX_SAFE_INTEGER \/\/ 2^53 -1\n\n<\/pre><\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>\u6570\u5b57\u683c\u5f0f\u5316\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\n(12345.678).toFixed(2) \/\/ &quot;12345.68&quot;\n\n<\/pre><\/div>\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">3\ufe0f\u20e3 String\uff08\u5b57\u7b26\u4e32\u7c7b\u578b\uff09<\/h1>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nconst str = &quot;Hello World&quot;;\n\n<\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u5c0f\u6280\u5de7\uff1a<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u6a21\u677f\u5b57\u7b26\u4e32\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nconst name = &quot;Alice&quot;;\nconst msg = `Hello, ${name}!`; \/\/ Hello, Alice!\n\n<\/pre><\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>\u5b57\u7b26\u4e32\u5207\u7247\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nstr.slice(0,5) \/\/ &quot;Hello&quot;\n\n<\/pre><\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>\u5b57\u7b26\u4e32\u8f6c\u6570\u5b57\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nNumber(&quot;123&quot;) \/\/ 123\nparseInt(&quot;123.45&quot;) \/\/ 123\n\n<\/pre><\/div>\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">4\ufe0f\u20e3 Boolean\uff08\u5e03\u5c14\u7c7b\u578b\uff09<\/h1>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nconst isTrue = true;\n\n<\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u5c0f\u6280\u5de7\uff1a<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5feb\u901f\u8f6c\u6362\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\n!!0       \/\/ false\n!!&quot;abc&quot;   \/\/ true\n\n<\/pre><\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>\u903b\u8f91\u8fd0\u7b97\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\ntrue &amp;amp;&amp;amp; false \/\/ false\ntrue || false \/\/ true\n\n<\/pre><\/div>\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">5\ufe0f\u20e3 Symbol\uff08\u7b26\u53f7\u7c7b\u578b\uff09<\/h1>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nconst sym = Symbol(&#039;id&#039;);\n\n<\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u5c0f\u6280\u5de7\uff1a<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u4fdd\u8bc1\u5bf9\u8c61\u5c5e\u6027\u552f\u4e00\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nconst obj = {};\nconst key = Symbol(&#039;key&#039;);\nobj&#x5B;key] = 123;\nconsole.log(obj&#x5B;key]); \/\/ 123\n\n<\/pre><\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>\u9632\u6b62\u547d\u540d\u51b2\u7a81\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nconst id1 = Symbol(&#039;id&#039;);\nconst id2 = Symbol(&#039;id&#039;);\nconsole.log(id1 === id2); \/\/ false\n\n<\/pre><\/div>\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">6\ufe0f\u20e3 BigInt\uff08\u5927\u6574\u6570\u7c7b\u578b\uff09<\/h1>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nconst big = 123456789012345678901234567890n;\n\n<\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u5c0f\u6280\u5de7\uff1a<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u652f\u6301\u8d85\u5927\u6574\u6570\u8fd0\u7b97\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nconst a = 9007199254740993n;\nconst b = 10n;\nconsole.log(a + b); \/\/ 9007199254741003n\n\n<\/pre><\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>\u6ce8\u610f\uff1aBigInt \u548c Number <strong>\u4e0d\u80fd\u76f4\u63a5\u6df7\u5408\u8fd0\u7b97<\/strong><\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">7\ufe0f\u20e3 undefined \u4e0e null<\/h1>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nlet a;       \/\/ undefined\nlet b = null; \/\/ null\n\n<\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u5c0f\u6280\u5de7\uff1a<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u533a\u522b\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\ntypeof undefined \/\/ &quot;undefined&quot;\ntypeof null      \/\/ &quot;object&quot; \uff08\u5386\u53f2\u9057\u7559\u95ee\u9898\uff09\n\n<\/pre><\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>\u5feb\u901f\u5224\u65ad\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nif (a == null) { \/\/ a \u4e3a null \u6216 undefined\n  console.log(&#039;\u7a7a\u503c&#039;);\n}\n\n<\/pre><\/div>\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">8\ufe0f\u20e3 Object\uff08\u5bf9\u8c61\u7c7b\u578b\uff09<\/h1>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nconst obj = { name: &#039;Alice&#039;, age: 20 };\nconst arr = &#x5B;1,2,3];\nconst func = () =&gt; 42;\n\n<\/pre><\/div>\n\n\n<h3 class=\"wp-block-heading\">\u5c0f\u6280\u5de7\uff1a<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u514b\u9686\u5bf9\u8c61\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nconst newObj = {...obj}; \/\/ \u6d45\u62f7\u8d1d\n\n<\/pre><\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>\u6df1\u62f7\u8d1d\uff08\u7b80\u5355\u573a\u666f\uff09\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nconst deep = JSON.parse(JSON.stringify(obj));\n\n<\/pre><\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>\u5224\u65ad\u6570\u7ec4\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nArray.isArray(arr) \/\/ true\n\n<\/pre><\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>\u5bf9\u8c61\u904d\u5386\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nfor (let key in obj) console.log(key, obj&#x5B;key]);\nObject.keys(obj).forEach(k =&gt; console.log(k, obj&#x5B;k]));\n\n<\/pre><\/div>\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">9\ufe0f\u20e3 typeof \u5feb\u901f\u603b\u7ed3<\/h1>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>\u7c7b\u578b<\/th><th>typeof \u8fd4\u56de\u503c<\/th><\/tr><\/thead><tbody><tr><td>Number<\/td><td>&#8220;number&#8221;<\/td><\/tr><tr><td>String<\/td><td>&#8220;string&#8221;<\/td><\/tr><tr><td>Boolean<\/td><td>&#8220;boolean&#8221;<\/td><\/tr><tr><td>Symbol<\/td><td>&#8220;symbol&#8221;<\/td><\/tr><tr><td>BigInt<\/td><td>&#8220;bigint&#8221;<\/td><\/tr><tr><td>undefined<\/td><td>&#8220;undefined&#8221;<\/td><\/tr><tr><td>null<\/td><td>&#8220;object&#8221;<\/td><\/tr><tr><td>Object\/Array\/Function<\/td><td>&#8220;object&#8221; \/ &#8220;function&#8221;<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p>\u2705 \u5c0f\u6280\u5de7\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5224\u65ad null \u548c\u5bf9\u8c61\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\nvalue === null\ntypeof value === &#039;object&#039; &amp;amp;&amp;amp; value !== null\n\n<\/pre><\/div>\n\n\n<ul class=\"wp-block-list\">\n<li>\u5224\u65ad\u51fd\u6570\uff1a<\/li>\n<\/ul>\n\n\n<div class=\"wp-block-syntaxhighlighter-code \"><pre class=\"brush: plain; title: ; notranslate\" title=\"\">\ntypeof func === &#039;function&#039;\n\n<\/pre><\/div>\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h1 class=\"wp-block-heading\">10\ufe0f\u20e3 \u5b9e\u7528\u6280\u5de7\u603b\u7ed3<\/h1>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>\u5b89\u5168\u8f6c\u6362<\/strong>\uff1a<code>Number()<\/code>, <code>String()<\/code>, <code>Boolean()<\/code><\/li>\n\n\n\n<li><strong>\u7a7a\u503c\u5224\u65ad<\/strong>\uff1a<code>value == null<\/code> \u540c\u65f6\u5224\u65ad null\/undefined<\/li>\n\n\n\n<li><strong>\u6570\u7ec4\u5224\u65ad<\/strong>\uff1a<code>Array.isArray()<\/code><\/li>\n\n\n\n<li><strong>\u6df1\u62f7\u8d1d\u5bf9\u8c61<\/strong>\uff1a<code>JSON.parse(JSON.stringify(obj))<\/code><\/li>\n\n\n\n<li><strong>\u7b26\u53f7\u552f\u4e00\u6027<\/strong>\uff1a<code>Symbol()<\/code><\/li>\n\n\n\n<li><strong>\u5927\u6570\u5b89\u5168\u8fd0\u7b97<\/strong>\uff1a<code>BigInt<\/code><\/li>\n\n\n\n<li><strong>\u6a21\u677f\u5b57\u7b26\u4e32\u66ff\u4ee3\u62fc\u63a5<\/strong>\uff1a<code>`${}`<\/code><\/li>\n\n\n\n<li><strong>\u5feb\u901f\u5e03\u5c14\u8f6c\u6362<\/strong>\uff1a<code>!!value<\/code><\/li>\n<\/ol>\n","protected":false},"excerpt":{"rendered":"<p>\u4e0b\u9762\u7ed9\u4f60\u6574\u7406\u4e00\u4efd \u9488\u5bf9\u521d\u5b66\u8005\u7684 JavaScript \u516b\u79cd\u7c7b\u578b\u5b9e\u7528\u5c0f\u6280\u5de7\u603b\u7ed3\uff0c\u4ece&#8230; <a class=\"more-link\" href=\"https:\/\/www.52runoob.com\/index.php\/2025\/12\/05\/%e9%92%88%e5%af%b9%e5%88%9d%e5%ad%a6%e8%80%85%e7%9a%84javascript%e5%85%ab%e7%a7%8d%e7%b1%bb%e5%9e%8b%e5%ae%9e%e7%94%a8%e5%b0%8f%e6%8a%80%e5%b7%a7%e6%80%bb%e7%bb%93\/\">Continue Reading &rarr;<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[49],"tags":[],"class_list":["post-504","post","type-post","status-publish","format-standard","hentry","category-javascript"],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/www.52runoob.com\/index.php\/wp-json\/wp\/v2\/posts\/504","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.52runoob.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.52runoob.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.52runoob.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.52runoob.com\/index.php\/wp-json\/wp\/v2\/comments?post=504"}],"version-history":[{"count":1,"href":"https:\/\/www.52runoob.com\/index.php\/wp-json\/wp\/v2\/posts\/504\/revisions"}],"predecessor-version":[{"id":505,"href":"https:\/\/www.52runoob.com\/index.php\/wp-json\/wp\/v2\/posts\/504\/revisions\/505"}],"wp:attachment":[{"href":"https:\/\/www.52runoob.com\/index.php\/wp-json\/wp\/v2\/media?parent=504"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.52runoob.com\/index.php\/wp-json\/wp\/v2\/categories?post=504"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.52runoob.com\/index.php\/wp-json\/wp\/v2\/tags?post=504"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}