{"id":635,"date":"2024-06-04T17:56:00","date_gmt":"2024-06-04T09:56:00","guid":{"rendered":"https:\/\/levin.ink\/?p=635"},"modified":"2024-06-17T23:33:25","modified_gmt":"2024-06-17T15:33:25","slug":"js-3-7-%e5%8e%9f%e5%9e%8b%e7%bb%a7%e6%89%bf","status":"publish","type":"post","link":"https:\/\/levin.ink\/?p=635","title":{"rendered":"JS &#8211; 3-7 \u539f\u578b\u7ee7\u627f"},"content":{"rendered":"<h1>\u539f\u578b\u7ee7\u627f<\/h1>\n<p>\u5728\u7f16\u7a0b\u4e2d\uff0c\u6211\u4eec\u7ecf\u5e38\u4f1a\u60f3\u83b7\u53d6\u5e76\u6269\u5c55\u4e00\u4e9b\u4e1c\u897f\u3002<br \/>\n\u4f8b\u5982\uff0c\u6211\u4eec\u6709\u4e00\u4e2a\u00a0<code>user<\/code>\u00a0\u5bf9\u8c61\u53ca\u5176\u5c5e\u6027\u548c\u65b9\u6cd5\uff0c\u5e76\u5e0c\u671b\u5c06\u00a0<code>admin<\/code>\u00a0\u548c\u00a0<code>guest<\/code>\u00a0\u4f5c\u4e3a\u57fa\u4e8e\u00a0<code>user<\/code>\u00a0\u7a0d\u52a0\u4fee\u6539\u7684\u53d8\u4f53\u3002\u6211\u4eec\u60f3\u91cd\u7528\u00a0<code>user<\/code>\u00a0\u4e2d\u7684\u5185\u5bb9\uff0c\u800c\u4e0d\u662f\u590d\u5236\/\u91cd\u65b0\u5b9e\u73b0\u5b83\u7684\u65b9\u6cd5\uff0c\u800c\u53ea\u662f\u5728\u5176\u4e4b\u4e0a\u6784\u5efa\u4e00\u4e2a\u65b0\u7684\u5bf9\u8c61\u3002<br \/>\n<strong>\u539f\u578b\u7ee7\u627f\uff08Prototypal inheritance\uff09<\/strong>\u00a0\u8fd9\u4e2a\u8bed\u8a00\u7279\u6027\u80fd\u591f\u5e2e\u52a9\u6211\u4eec\u5b9e\u73b0\u8fd9\u4e00\u9700\u6c42\u3002<\/p>\n<h2>[[prototype]]<\/h2>\n<p>\u5728 JavaScript \u4e2d\uff0c\u5bf9\u8c61\u6709\u4e00\u4e2a\u7279\u6b8a\u7684\u9690\u85cf\u5c5e\u6027\u00a0<code>[[Prototype]]<\/code>\uff08\u5982\u89c4\u8303\u4e2d\u6240\u547d\u540d\u7684\uff09\uff0c\u5b83\u8981\u4e48\u4e3a\u00a0<code>null<\/code>\uff0c\u8981\u4e48\u5c31\u662f\u5bf9\u53e6\u4e00\u4e2a\u5bf9\u8c61\u7684\u5f15\u7528\u3002\u8be5\u5bf9\u8c61\u88ab\u79f0\u4e3a\u201c\u539f\u578b\u201d<br \/>\n\u5f53\u6211\u4eec\u4ece\u00a0<code>object<\/code>\u00a0\u4e2d\u8bfb\u53d6\u4e00\u4e2a\u7f3a\u5931\u7684\u5c5e\u6027\u65f6\uff0cJavaScript \u4f1a\u81ea\u52a8\u4ece\u539f\u578b\u4e2d\u83b7\u53d6\u8be5\u5c5e\u6027\u3002\u5728\u7f16\u7a0b\u4e2d\uff0c\u8fd9\u88ab\u79f0\u4e3a\u201c\u539f\u578b\u7ee7\u627f\u201d\u3002\u5f88\u5feb\uff0c\u6211\u4eec\u5c06\u901a\u8fc7\u5f88\u591a\u793a\u4f8b\u6765\u5b66\u4e60\u6b64\u7c7b\u7ee7\u627f\uff0c\u4ee5\u53ca\u57fa\u4e8e\u6b64\u7c7b\u7ee7\u627f\u7684\u66f4\u70ab\u9177\u7684\u8bed\u8a00\u529f\u80fd\u3002<br \/>\n\u5c5e\u6027\u00a0<code>[[Prototype]]<\/code>\u00a0\u662f\u5185\u90e8\u7684\u800c\u4e14\u662f\u9690\u85cf\u7684\uff0c\u4f46\u662f\u8fd9\u513f\u6709\u5f88\u591a\u8bbe\u7f6e\u5b83\u7684\u65b9\u5f0f\u3002<br \/>\n\u5176\u4e2d\u4e4b\u4e00\u5c31\u662f\u4f7f\u7528\u7279\u6b8a\u7684\u540d\u5b57\u00a0<code>__proto__<\/code>\uff0c\u5c31\u50cf\u8fd9\u6837<\/p>\n<pre><code class=\"language-js\">let animal = {\n  eats: true\n};\nlet rabbit = {\n  jumps: true\n};\n\nrabbit.__proto__ = animal; \/\/ \u8bbe\u7f6e rabbit.[[Prototype]] = animal\n<\/code><\/pre>\n<p>\u73b0\u5728\uff0c\u5982\u679c\u6211\u4eec\u4ece\u00a0<code>rabbit<\/code>\u00a0\u4e2d\u8bfb\u53d6\u4e00\u4e2a\u5b83\u6ca1\u6709\u7684\u5c5e\u6027\uff0cJavaScript \u4f1a\u81ea\u52a8\u4ece\u00a0<code>animal<\/code>\u00a0\u4e2d\u83b7\u53d6\u3002<br \/>\n\u5f53\u00a0<code>alert<\/code>\u00a0\u8bd5\u56fe\u8bfb\u53d6\u00a0<code>rabbit.eats<\/code>\u00a0<code>(**)<\/code>\u00a0\u65f6\uff0c\u56e0\u4e3a\u5b83\u4e0d\u5b58\u5728\u4e8e\u00a0<code>rabbit<\/code>\u00a0\u4e2d\uff0c\u6240\u4ee5 JavaScript \u4f1a\u987a\u7740\u00a0<code>[[Prototype]]<\/code>\u00a0\u5f15\u7528\uff0c\u5728\u00a0<code>animal<\/code>\u00a0\u4e2d\u67e5\u627e\uff08\u81ea\u4e0b\u800c\u4e0a\uff09<br \/>\n\u5728\u8fd9\u513f\u6211\u4eec\u53ef\u4ee5\u8bf4 &quot;<code>animal<\/code>\u00a0\u662f\u00a0<code>rabbit<\/code>\u00a0\u7684\u539f\u578b&quot;\uff0c\u6216\u8005\u8bf4 &quot;<code>rabbit<\/code>\u00a0\u7684\u539f\u578b\u662f\u4ece\u00a0<code>animal<\/code>\u00a0\u7ee7\u627f\u800c\u6765\u7684&quot;\u3002<br \/>\n\u56e0\u6b64\uff0c\u5982\u679c\u00a0<code>animal<\/code>\u00a0\u6709\u8bb8\u591a\u6709\u7528\u7684\u5c5e\u6027\u548c\u65b9\u6cd5\uff0c\u90a3\u4e48\u5b83\u4eec\u5c06\u81ea\u52a8\u5730\u53d8\u4e3a\u5728\u00a0<code>rabbit<\/code>\u00a0\u4e2d\u53ef\u7528\u3002\u8fd9\u79cd\u5c5e\u6027\u88ab\u79f0\u4e3a\u201c\u7ee7\u627f\u201d\u3002<br \/>\n\u539f\u578b\u94fe\u53ef\u4ee5\u5f88\u957f<br \/>\n\u73b0\u5728\uff0c\u5982\u679c\u6211\u4eec\u4ece\u00a0<code>longEar<\/code>\u00a0\u4e2d\u8bfb\u53d6\u4e00\u4e9b\u5b83\u4e0d\u5b58\u5728\u7684\u5185\u5bb9\uff0cJavaScript \u4f1a\u5148\u5728\u00a0<code>rabbit<\/code>\u00a0\u4e2d\u67e5\u627e\uff0c\u7136\u540e\u5728\u00a0<code>animal<\/code>\u00a0\u4e2d\u67e5\u627e\u3002<br \/>\n\u8fd9\u91cc\u53ea\u6709\u4e24\u4e2a\u9650\u5236\uff1a<\/p>\n<ol>\n<li>\u5f15\u7528\u4e0d\u80fd\u5f62\u6210\u95ed\u73af\u3002\u5982\u679c\u6211\u4eec\u8bd5\u56fe\u7ed9\u00a0<code>__proto__<\/code>\u00a0\u8d4b\u503c\u4f46\u4f1a\u5bfc\u81f4\u5f15\u7528\u5f62\u6210\u95ed\u73af\u65f6\uff0cJavaScript \u4f1a\u629b\u51fa\u9519\u8bef\u3002<\/li>\n<li><code>__proto__<\/code>\u00a0\u7684\u503c\u53ef\u4ee5\u662f\u5bf9\u8c61\uff0c\u4e5f\u53ef\u4ee5\u662f\u00a0<code>null<\/code>\u3002\u800c\u5176\u4ed6\u7684\u7c7b\u578b\u90fd\u4f1a\u88ab\u5ffd\u7565\u3002<br \/>\n\u5f53\u7136\uff0c\u8fd9\u53ef\u80fd\u5f88\u663e\u800c\u6613\u89c1\uff0c\u4f46\u662f\u4ecd\u7136\u8981\u5f3a\u8c03\uff1a\u53ea\u80fd\u6709\u4e00\u4e2a\u00a0<code>[[Prototype]]<\/code>\u3002\u4e00\u4e2a\u5bf9\u8c61\u4e0d\u80fd\u4ece\u5176\u4ed6\u4e24\u4e2a\u5bf9\u8c61\u83b7\u5f97\u7ee7\u627f\u3002<\/li>\n<\/ol>\n<blockquote>\n<p><code>__proto__<\/code>\u00a0\u662f\u00a0<code>[[Prototype]]<\/code>\u00a0\u7684\u56e0\u5386\u53f2\u539f\u56e0\u800c\u7559\u4e0b\u6765\u7684 getter\/setter<br \/>\n\u521d\u5b66\u8005\u5e38\u72af\u4e00\u4e2a\u666e\u904d\u7684\u9519\u8bef\uff0c\u5c31\u662f\u4e0d\u77e5\u9053\u00a0<code>__proto__<\/code>\u00a0\u548c\u00a0<code>[[Prototype]]<\/code>\u00a0\u7684\u533a\u522b\u3002<br \/>\n\u8bf7\u6ce8\u610f\uff0c<code>__proto__<\/code>\u00a0\u4e0e\u5185\u90e8\u7684\u00a0<code>[[Prototype]]<\/code>\u00a0<strong>\u4e0d\u4e00\u6837<\/strong>\u3002<code>__proto__<\/code>\u00a0\u662f\u00a0<code>[[Prototype]]<\/code>\u00a0\u7684 getter\/setter\u3002\u7a0d\u540e\uff0c\u6211\u4eec\u5c06\u770b\u5230\u5728\u4ec0\u4e48\u60c5\u51b5\u4e0b\u7406\u89e3\u5b83\u4eec\u5f88\u91cd\u8981\uff0c\u5728\u5efa\u7acb\u5bf9 JavaScript \u8bed\u8a00\u7684\u7406\u89e3\u65f6\uff0c\u8ba9\u6211\u4eec\u7262\u8bb0\u8fd9\u4e00\u70b9\u3002<br \/>\n<code>__proto__<\/code>\u00a0\u5c5e\u6027\u6709\u70b9\u8fc7\u65f6\u4e86\u3002\u5b83\u7684\u5b58\u5728\u662f\u51fa\u4e8e\u5386\u53f2\u7684\u539f\u56e0\uff0c\u73b0\u4ee3\u7f16\u7a0b\u8bed\u8a00\u5efa\u8bae\u6211\u4eec\u5e94\u8be5\u4f7f\u7528\u51fd\u6570\u00a0<code>Object.getPrototypeOf\/Object.setPrototypeOf<\/code>\u00a0\u6765\u53d6\u4ee3\u00a0<code>__proto__<\/code>\u00a0\u53bb get\/set \u539f\u578b\u3002\u7a0d\u540e\u6211\u4eec\u5c06\u4ecb\u7ecd\u8fd9\u4e9b\u51fd\u6570\u3002<br \/>\n\u6839\u636e\u89c4\u8303\uff0c<code>__proto__<\/code>\u00a0\u5fc5\u987b\u4ec5\u53d7\u6d4f\u89c8\u5668\u73af\u5883\u7684\u652f\u6301\u3002\u4f46\u5b9e\u9645\u4e0a\uff0c\u5305\u62ec\u670d\u52a1\u7aef\u5728\u5185\u7684\u6240\u6709\u73af\u5883\u90fd\u652f\u6301\u5b83\uff0c\u56e0\u6b64\u6211\u4eec\u4f7f\u7528\u5b83\u662f\u975e\u5e38\u5b89\u5168\u7684\u3002<br \/>\n\u7531\u4e8e\u00a0<code>__proto__<\/code>\u00a0\u6807\u8bb0\u5728\u89c2\u611f\u4e0a\u66f4\u52a0\u660e\u663e\uff0c\u6240\u4ee5\u6211\u4eec\u5728\u540e\u9762\u7684\u793a\u4f8b\u4e2d\u5c06\u4f7f\u7528\u5b83\u3002<\/p>\n<\/blockquote>\n<h2>\u5199\u5165\u4e0d\u4f7f\u7528\u539f\u578b<\/h2>\n<p>\u539f\u578b\u4ec5\u7528\u4e8e\u8bfb\u53d6\u5c5e\u6027\u3002<br \/>\n\u5bf9\u4e8e\u5199\u5165\/\u5220\u9664\u64cd\u4f5c\u53ef\u4ee5\u76f4\u63a5\u5728\u5bf9\u8c61\u4e0a\u8fdb\u884c\u3002<\/p>\n<pre><code class=\"language-js\">let animal = {\n  eats: true,\n  walk() {\n    \/* rabbit \u4e0d\u4f1a\u4f7f\u7528\u6b64\u65b9\u6cd5 *\/\n  }\n};\n\nlet rabbit = {\n  __proto__: animal\n};\n\nrabbit.walk = function() {\n  alert(&quot;Rabbit! Bounce-bounce!&quot;);\n};\n\nrabbit.walk(); \/\/ Rabbit! Bounce-bounce!\n<\/code><\/pre>\n<p>\u8bbf\u95ee\u5668\uff08accessor\uff09\u5c5e\u6027\u662f\u4e00\u4e2a\u4f8b\u5916\uff0c\u56e0\u4e3a\u8d4b\u503c\uff08assignment\uff09\u64cd\u4f5c\u662f\u7531 setter \u51fd\u6570\u5904\u7406\u7684\u3002\u56e0\u6b64\uff0c\u5199\u5165\u6b64\u7c7b\u5c5e\u6027\u5b9e\u9645\u4e0a\u4e0e\u8c03\u7528\u51fd\u6570\u76f8\u540c\u3002<br \/>\n\u4e5f\u5c31\u662f\u8fd9\u4e2a\u539f\u56e0\uff0c\u6240\u4ee5\u4e0b\u9762\u8fd9\u6bb5\u4ee3\u7801\u4e2d\u7684\u00a0<code>admin.fullName<\/code>\u00a0\u80fd\u591f\u6b63\u5e38\u8fd0\u884c\uff1a<\/p>\n<pre><code class=\"language-js\">let user = {\n  name: &quot;John&quot;,\n  surname: &quot;Smith&quot;,\n\n  set fullName(value) {\n    [this.name, this.surname] = value.split(&quot; &quot;);\n  },\n\n  get fullName() {\n    return `${this.name} ${this.surname}`;\n  }\n};\n\nlet admin = {\n  __proto__: user,\n  isAdmin: true\n};\n\nalert(admin.fullName); \/\/ John Smith (*)\n\n\/\/ setter triggers!\nadmin.fullName = &quot;Alice Cooper&quot;; \/\/ (**)\n\nalert(admin.fullName); \/\/ Alice Cooper\uff0cadmin \u7684\u5185\u5bb9\u88ab\u4fee\u6539\u4e86\nalert(user.fullName);  \/\/ John Smith\uff0cuser \u7684\u5185\u5bb9\u88ab\u4fdd\u62a4\u4e86\n<\/code><\/pre>\n<p>\u5728\u00a0<code>(*)<\/code>\u00a0\u884c\u4e2d\uff0c\u5c5e\u6027\u00a0<code>admin.fullName<\/code>\u00a0\u5728\u539f\u578b\u00a0<code>user<\/code>\u00a0\u4e2d\u6709\u4e00\u4e2a getter\uff0c\u56e0\u6b64\u5b83\u4f1a\u88ab\u8c03\u7528\u3002\u5728\u00a0<code>(**)<\/code>\u00a0\u884c\u4e2d\uff0c\u5c5e\u6027\u5728\u539f\u578b\u4e2d\u6709\u4e00\u4e2a setter\uff0c\u56e0\u6b64\u5b83\u4f1a\u88ab\u8c03\u7528\u3002<\/p>\n<h2>this \u7684\u503c<\/h2>\n<p>\u5728\u4e0a\u9762\u7684\u4f8b\u5b50\u4e2d\u53ef\u80fd\u4f1a\u51fa\u73b0\u4e00\u4e2a\u6709\u8da3\u7684\u95ee\u9898\uff1a\u5728\u00a0<code>set fullName(value)<\/code>\u00a0\u4e2d\u00a0<code>this<\/code>\u00a0\u7684\u503c\u662f\u4ec0\u4e48\uff1f\u5c5e\u6027\u00a0<code>this.name<\/code>\u00a0\u548c\u00a0<code>this.surname<\/code>\u00a0\u88ab\u5199\u5728\u54ea\u91cc\uff1a\u5728\u00a0<code>user<\/code>\u00a0\u8fd8\u662f\u00a0<code>admin<\/code>\uff1f<br \/>\n\u7b54\u6848\u5f88\u7b80\u5355\uff1a<code>this<\/code>\u00a0\u6839\u672c\u4e0d\u53d7\u539f\u578b\u7684\u5f71\u54cd\u3002<br \/>\n<strong>\u65e0\u8bba\u5728\u54ea\u91cc\u627e\u5230\u65b9\u6cd5\uff1a\u5728\u4e00\u4e2a\u5bf9\u8c61\u8fd8\u662f\u5728\u539f\u578b\u4e2d\u3002\u5728\u4e00\u4e2a\u65b9\u6cd5\u8c03\u7528\u4e2d\uff0c<code>this<\/code>\u00a0\u59cb\u7ec8\u662f\u70b9\u7b26\u53f7\u00a0<code>.<\/code>\u00a0\u524d\u9762\u7684\u5bf9\u8c61\u3002<\/strong><br \/>\n\u56e0\u6b64\uff0csetter \u8c03\u7528\u00a0<code>admin.fullName=<\/code>\u00a0\u4f7f\u7528\u00a0<code>admin<\/code>\u00a0\u4f5c\u4e3a\u00a0<code>this<\/code>\uff0c\u800c\u4e0d\u662f\u00a0<code>user<\/code>\u3002<br \/>\n\u8fd9\u662f\u4e00\u4ef6\u975e\u5e38\u91cd\u8981\u7684\u4e8b\u513f\uff0c\u56e0\u4e3a\u6211\u4eec\u53ef\u80fd\u6709\u4e00\u4e2a\u5e26\u6709\u5f88\u591a\u65b9\u6cd5\u7684\u5927\u5bf9\u8c61\uff0c\u5e76\u4e14\u8fd8\u6709\u4ece\u5176\u7ee7\u627f\u7684\u5bf9\u8c61\u3002\u5f53\u7ee7\u627f\u7684\u5bf9\u8c61\u8fd0\u884c\u7ee7\u627f\u7684\u65b9\u6cd5\u65f6\uff0c\u5b83\u4eec\u5c06\u4ec5\u4fee\u6539\u81ea\u5df1\u7684\u72b6\u6001\uff0c\u800c\u4e0d\u4f1a\u4fee\u6539\u5927\u5bf9\u8c61\u7684\u72b6\u6001\u3002<br \/>\n\u4f8b\u5982\uff0c\u8fd9\u91cc\u7684\u00a0<code>animal<\/code>\u00a0\u4ee3\u8868\u201c\u65b9\u6cd5\u5b58\u50a8\u201d\uff0c<code>rabbit<\/code>\u00a0\u5728\u4f7f\u7528\u5176\u4e2d\u7684\u65b9\u6cd5\u3002<br \/>\n\u8c03\u7528\u00a0<code>rabbit.sleep()<\/code>\u00a0\u4f1a\u5728\u00a0<code>rabbit<\/code>\u00a0\u5bf9\u8c61\u4e0a\u8bbe\u7f6e\u00a0<code>this.isSleeping<\/code>\uff1a<\/p>\n<pre><code class=\"language-js\">\/\/ animal \u6709\u4e00\u4e9b\u65b9\u6cd5\nlet animal = {\n  walk() {\n    if (!this.isSleeping) {\n      alert(`I walk`);\n    }\n  },\n  sleep() {\n    this.isSleeping = true;\n  }\n};\n\nlet rabbit = {\n  name: &quot;White Rabbit&quot;,\n  __proto__: animal\n};\n\n\/\/ \u4fee\u6539 rabbit.isSleeping\nrabbit.sleep();\n\nalert(rabbit.isSleeping); \/\/ true\nalert(animal.isSleeping); \/\/ undefined\uff08\u539f\u578b\u4e2d\u6ca1\u6709\u6b64\u5c5e\u6027\uff09\n<\/code><\/pre>\n<p>\u5982\u679c\u6211\u4eec\u8fd8\u6709\u4ece\u00a0<code>animal<\/code>\u00a0\u7ee7\u627f\u7684\u5176\u4ed6\u5bf9\u8c61\uff0c\u50cf\u00a0<code>bird<\/code>\u00a0\u548c\u00a0<code>snake<\/code>\u00a0\u7b49\uff0c\u5b83\u4eec\u4e5f\u5c06\u53ef\u4ee5\u8bbf\u95ee\u00a0<code>animal<\/code>\u00a0\u7684\u65b9\u6cd5\u3002\u4f46\u662f\uff0c\u6bcf\u4e2a\u65b9\u6cd5\u8c03\u7528\u4e2d\u7684\u00a0<code>this<\/code>\u00a0\u90fd\u662f\u5728\u8c03\u7528\u65f6\uff08\u70b9\u7b26\u53f7\u524d\uff09\u8bc4\u4f30\u7684\u5bf9\u5e94\u7684\u5bf9\u8c61\uff0c\u800c\u4e0d\u662f\u00a0<code>animal<\/code>\u3002\u56e0\u6b64\uff0c\u5f53\u6211\u4eec\u5c06\u6570\u636e\u5199\u5165\u00a0<code>this<\/code>\u00a0\u65f6\uff0c\u4f1a\u5c06\u5176\u5b58\u50a8\u5230\u8fd9\u4e9b\u5bf9\u8c61\u4e2d\u3002<br \/>\n\u6240\u4ee5\uff0c\u65b9\u6cd5\u662f\u5171\u4eab\u7684\uff0c\u4f46\u5bf9\u8c61\u72b6\u6001\u4e0d\u662f\u3002<\/p>\n<h2>for...in \u5faa\u73af<\/h2>\n<p><code>for..in<\/code>\u00a0\u5faa\u73af\u4e5f\u4f1a\u8fed\u4ee3\u7ee7\u627f\u7684\u5c5e\u6027\u3002<\/p>\n<pre><code class=\"language-js\">let animal = {\n  eats: true\n};\n\nlet rabbit = {\n  jumps: true,\n  __proto__: animal\n};\n\n\/\/ Object.keys \u53ea\u8fd4\u56de\u81ea\u5df1\u7684 key\nalert(Object.keys(rabbit)); \/\/ jumps\n\n\/\/ for..in \u4f1a\u904d\u5386\u81ea\u5df1\u4ee5\u53ca\u7ee7\u627f\u7684\u952e\nfor(let prop in rabbit) alert(prop); \/\/ jumps\uff0c\u7136\u540e\u662f eats\n<\/code><\/pre>\n<p>\u5982\u679c\u8fd9\u4e0d\u662f\u6211\u4eec\u60f3\u8981\u7684\uff0c\u5e76\u4e14\u6211\u4eec\u60f3\u6392\u9664\u7ee7\u627f\u7684\u5c5e\u6027\uff0c\u90a3\u4e48\u8fd9\u513f\u6709\u4e00\u4e2a\u5185\u5efa\u65b9\u6cd5\u00a0<a href=\"https:\/\/developer.mozilla.org\/en-US\/docs\/Web\/JavaScript\/Reference\/Global_Objects\/Object\/hasOwnProperty\">obj.hasOwnProperty(key)<\/a>\uff1a\u5982\u679c\u00a0<code>obj<\/code>\u00a0\u5177\u6709\u81ea\u5df1\u7684\uff08\u975e\u7ee7\u627f\u7684\uff09\u540d\u4e3a\u00a0<code>key<\/code>\u00a0\u7684\u5c5e\u6027\uff0c\u5219\u8fd4\u56de\u00a0<code>true<\/code>\u3002<br \/>\n\u56e0\u6b64\uff0c\u6211\u4eec\u53ef\u4ee5\u8fc7\u6ee4\u6389\u7ee7\u627f\u7684\u5c5e\u6027\uff08\u6216\u5bf9\u5b83\u4eec\u8fdb\u884c\u5176\u4ed6\u64cd\u4f5c\uff09\uff1a<\/p>\n<pre><code class=\"language-js\">let animal = {\n  eats: true\n};\n\nlet rabbit = {\n  jumps: true,\n  __proto__: animal\n};\n\nfor(let prop in rabbit) {\n  let isOwn = rabbit.hasOwnProperty(prop);\n\n  if (isOwn) {\n    alert(`Our: ${prop}`); \/\/ Our: jumps\n  } else {\n    alert(`Inherited: ${prop}`); \/\/ Inherited: eats\n  }\n}\n<\/code><\/pre>\n<p>\u8fd9\u91cc\u6211\u4eec\u6709\u4ee5\u4e0b\u7ee7\u627f\u94fe\uff1a<code>rabbit<\/code>\u00a0\u4ece\u00a0<code>animal<\/code>\u00a0\u4e2d\u7ee7\u627f\uff0c<code>animal<\/code>\u00a0\u4ece\u00a0<code>Object.prototype<\/code>\u00a0\u4e2d\u7ee7\u627f\uff08\u56e0\u4e3a\u00a0<code>animal<\/code>\u00a0\u662f\u5bf9\u8c61\u5b57\u9762\u91cf\u00a0<code>{...}<\/code>\uff0c\u6240\u4ee5\u8fd9\u662f\u9ed8\u8ba4\u7684\u7ee7\u627f\uff09\uff0c\u7136\u540e\u518d\u5411\u4e0a\u662f\u00a0<code>null<\/code><br \/>\n\u6ce8\u610f\uff0c\u8fd9\u6709\u4e00\u4ef6\u5f88\u6709\u8da3\u7684\u4e8b\u513f\u3002\u65b9\u6cd5\u00a0<code>rabbit.hasOwnProperty<\/code>\u00a0\u6765\u81ea\u54ea\u513f\uff1f\u6211\u4eec\u5e76\u6ca1\u6709\u5b9a\u4e49\u5b83\u3002\u4ece\u4e0a\u56fe\u4e2d\u7684\u539f\u578b\u94fe\u6211\u4eec\u53ef\u4ee5\u770b\u5230\uff0c\u8be5\u65b9\u6cd5\u662f\u00a0<code>Object.prototype.hasOwnProperty<\/code>\u00a0\u63d0\u4f9b\u7684\u3002\u6362\u53e5\u8bdd\u8bf4\uff0c\u5b83\u662f\u7ee7\u627f\u7684\u3002<br \/>\n\u2026\u2026\u5982\u679c\u00a0<code>for..in<\/code>\u00a0\u5faa\u73af\u4f1a\u5217\u51fa\u7ee7\u627f\u7684\u5c5e\u6027\uff0c\u90a3\u4e3a\u4ec0\u4e48\u00a0<code>hasOwnProperty<\/code>\u00a0\u6ca1\u6709\u50cf\u00a0<code>eats<\/code>\u00a0\u548c\u00a0<code>jumps<\/code>\u00a0\u90a3\u6837\u51fa\u73b0\u5728\u00a0<code>for..in<\/code>\u00a0\u5faa\u73af\u4e2d\uff1f<br \/>\n\u7b54\u6848\u5f88\u7b80\u5355\uff1a\u5b83\u662f\u4e0d\u53ef\u679a\u4e3e\u7684\u3002\u5c31\u50cf\u00a0<code>Object.prototype<\/code>\u00a0\u7684\u5176\u4ed6\u5c5e\u6027\uff0c<code>hasOwnProperty<\/code>\u00a0\u6709\u00a0<code>enumerable:false<\/code>\u00a0\u6807\u5fd7\u3002\u5e76\u4e14\u00a0<code>for..in<\/code>\u00a0\u53ea\u4f1a\u5217\u51fa\u53ef\u679a\u4e3e\u7684\u5c5e\u6027\u3002\u8fd9\u5c31\u662f\u4e3a\u4ec0\u4e48\u5b83\u548c\u5176\u4f59\u7684\u00a0<code>Object.prototype<\/code>\u00a0\u5c5e\u6027\u90fd\u672a\u88ab\u5217\u51fa\u3002<\/p>\n<blockquote>\n<p>\u51e0\u4e4e\u6240\u6709\u5176\u4ed6\u952e\/\u503c\u83b7\u53d6\u65b9\u6cd5\u90fd\u5ffd\u7565\u7ee7\u627f\u7684\u5c5e\u6027<br \/>\n\u51e0\u4e4e\u6240\u6709\u5176\u4ed6\u952e\/\u503c\u83b7\u53d6\u65b9\u6cd5\uff0c\u4f8b\u5982\u00a0<code>Object.keys<\/code>\u00a0\u548c\u00a0<code>Object.values<\/code>\u00a0\u7b49\uff0c\u90fd\u4f1a\u5ffd\u7565\u7ee7\u627f\u7684\u5c5e\u6027\u3002<br \/>\n\u5b83\u4eec\u53ea\u4f1a\u5bf9\u5bf9\u8c61\u81ea\u8eab\u8fdb\u884c\u64cd\u4f5c\u3002<strong>\u4e0d\u8003\u8651<\/strong>\u00a0\u7ee7\u627f\u81ea\u539f\u578b\u7684\u5c5e\u6027\u3002<\/p>\n<\/blockquote>\n<h1>F.prototype<\/h1>\n<p>\u6211\u4eec\u8fd8\u8bb0\u5f97\uff0c\u53ef\u4ee5\u4f7f\u7528\u8bf8\u5982\u00a0<code>new F()<\/code>\u00a0\u8fd9\u6837\u7684\u6784\u9020\u51fd\u6570\u6765\u521b\u5efa\u4e00\u4e2a\u65b0\u5bf9\u8c61\u3002<br \/>\n\u5982\u679c\u00a0<code>F.prototype<\/code>\u00a0\u662f\u4e00\u4e2a\u5bf9\u8c61\uff0c\u90a3\u4e48\u00a0<code>new<\/code>\u00a0\u64cd\u4f5c\u7b26\u4f1a\u4f7f\u7528\u5b83\u4e3a\u65b0\u5bf9\u8c61\u8bbe\u7f6e\u00a0<code>[[Prototype]]<\/code>\u3002<\/p>\n<blockquote>\n<p>\u8bf7\u6ce8\u610f\uff1a<br \/>\nJavaScript \u4ece\u4e00\u5f00\u59cb\u5c31\u6709\u4e86\u539f\u578b\u7ee7\u627f\u3002\u8fd9\u662f JavaScript \u7f16\u7a0b\u8bed\u8a00\u7684\u6838\u5fc3\u7279\u6027\u4e4b\u4e00\u3002<br \/>\n\u4f46\u662f\u5728\u8fc7\u53bb\uff0c\u6ca1\u6709\u76f4\u63a5\u5bf9\u5176\u8fdb\u884c\u8bbf\u95ee\u7684\u65b9\u5f0f\u3002\u552f\u4e00\u53ef\u9760\u7684\u65b9\u6cd5\u662f\u672c\u7ae0\u4e2d\u4f1a\u4ecb\u7ecd\u7684\u6784\u9020\u51fd\u6570\u7684\u00a0<code>&quot;prototype&quot;<\/code>\u00a0\u5c5e\u6027\u3002\u76ee\u524d\u4ecd\u6709\u8bb8\u591a\u811a\u672c\u4ecd\u5728\u4f7f\u7528\u5b83\u3002<\/p>\n<\/blockquote>\n<p>\u8bf7\u6ce8\u610f\uff0c\u8fd9\u91cc\u7684\u00a0<code>F.prototype<\/code>\u00a0\u6307\u7684\u662f\u00a0<code>F<\/code>\u00a0\u7684\u4e00\u4e2a\u540d\u4e3a\u00a0<code>&quot;prototype&quot;<\/code>\u00a0\u7684\u5e38\u89c4\u5c5e\u6027\u3002\u8fd9\u542c\u8d77\u6765\u4e0e\u201c\u539f\u578b\u201d\u8fd9\u4e2a\u672f\u8bed\u5f88\u7c7b\u4f3c\uff0c\u4f46\u8fd9\u91cc\u6211\u4eec\u5b9e\u9645\u4e0a\u6307\u7684\u662f\u5177\u6709\u8be5\u540d\u5b57\u7684\u5e38\u89c4\u5c5e\u6027\u3002<\/p>\n<pre><code class=\"language-js\">let animal = {\n  eats: true\n};\n\nfunction Rabbit(name) {\n  this.name = name;\n}\n\nRabbit.prototype = animal;\n\nlet rabbit = new Rabbit(&quot;White Rabbit&quot;); \/\/  rabbit.__proto__ == animal\n\nalert( rabbit.eats ); \/\/ true\n<\/code><\/pre>\n<p>\u8bbe\u7f6e\u00a0<code>Rabbit.prototype = animal<\/code>\u00a0\u7684\u5b57\u9762\u610f\u601d\u662f\uff1a\u201c\u5f53\u521b\u5efa\u4e86\u4e00\u4e2a\u00a0<code>new Rabbit<\/code>\u00a0\u65f6\uff0c\u628a\u5b83\u7684\u00a0<code>[[Prototype]]<\/code>\u00a0\u8d4b\u503c\u4e3a\u00a0<code>animal<\/code>\u201d\u3002<\/p>\n<blockquote>\n<p><code>F.prototype<\/code>\u00a0\u4ec5\u7528\u5728\u00a0<code>new F<\/code>\u00a0\u65f6<br \/>\n<code>F.prototype<\/code>\u00a0\u5c5e\u6027\u4ec5\u5728\u00a0<code>new F<\/code>\u00a0\u88ab\u8c03\u7528\u65f6\u4f7f\u7528\uff0c\u5b83\u4e3a\u65b0\u5bf9\u8c61\u7684\u00a0<code>[[Prototype]]<\/code>\u00a0\u8d4b\u503c\u3002<br \/>\n\u5982\u679c\u5728\u521b\u5efa\u4e4b\u540e\uff0c<code>F.prototype<\/code>\u00a0\u5c5e\u6027\u6709\u4e86\u53d8\u5316\uff08<code>F.prototype = &lt;another object&gt;<\/code>\uff09\uff0c\u90a3\u4e48\u901a\u8fc7\u00a0<code>new F<\/code>\u00a0\u521b\u5efa\u7684\u65b0\u5bf9\u8c61\u4e5f\u5c06\u968f\u4e4b\u62e5\u6709\u65b0\u7684\u5bf9\u8c61\u4f5c\u4e3a\u00a0<code>[[Prototype]]<\/code>\uff0c\u4f46\u5df2\u7ecf\u5b58\u5728\u7684\u5bf9\u8c61\u5c06\u4fdd\u6301\u65e7\u6709\u7684\u503c\u3002<\/p>\n<\/blockquote>\n<h2>\u9ed8\u8ba4\u7684 F.prototype \u6784\u9020\u5668\u5c5e\u6027<\/h2>\n<p>\u6bcf\u4e2a\u51fd\u6570\u90fd\u6709\u00a0<code>&quot;prototype&quot;<\/code>\u00a0\u5c5e\u6027\uff0c\u5373\u4f7f\u6211\u4eec\u6ca1\u6709\u63d0\u4f9b\u5b83\u3002<br \/>\n\u9ed8\u8ba4\u7684\u00a0<code>&quot;prototype&quot;<\/code>\u00a0\u662f\u4e00\u4e2a\u53ea\u6709\u5c5e\u6027\u00a0<code>constructor<\/code>\u00a0\u7684\u5bf9\u8c61\uff0c\u5c5e\u6027\u00a0<code>constructor<\/code>\u00a0\u6307\u5411\u51fd\u6570\u81ea\u8eab\u3002<br \/>\n\u901a\u5e38\uff0c\u5982\u679c\u6211\u4eec\u4ec0\u4e48\u90fd\u4e0d\u505a\uff0c<code>constructor<\/code>\u00a0\u5c5e\u6027\u53ef\u4ee5\u901a\u8fc7\u00a0<code>[[Prototype]]<\/code>\u00a0\u7ed9\u6240\u6709 rabbits \u4f7f\u7528<\/p>\n<pre><code class=\"language-js\">function Rabbit() {}\n\/\/ \u9ed8\u8ba4\uff1a\n\/\/ Rabbit.prototype = { constructor: Rabbit }\n\nalert( Rabbit.prototype.constructor == Rabbit ); \/\/ true\n\nlet rabbit = new Rabbit(); \/\/ \u7ee7\u627f\u81ea {constructor: Rabbit}\n\nalert(rabbit.constructor == Rabbit); \/\/ true (from prototype)\n<\/code><\/pre>\n<p>\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u00a0<code>constructor<\/code>\u00a0\u5c5e\u6027\u6765\u521b\u5efa\u4e00\u4e2a\u65b0\u5bf9\u8c61\uff0c\u8be5\u5bf9\u8c61\u4f7f\u7528\u4e0e\u73b0\u6709\u5bf9\u8c61\u76f8\u540c\u7684\u6784\u9020\u5668\u3002<\/p>\n<pre><code class=\"language-js\">function Rabbit(name) {\n  this.name = name;\n  alert(name);\n}\n\nlet rabbit = new Rabbit(&quot;White Rabbit&quot;);\n\nlet rabbit2 = new rabbit.constructor(&quot;Black Rabbit&quot;);\n<\/code><\/pre>\n<p>\u5f53\u6211\u4eec\u6709\u4e00\u4e2a\u5bf9\u8c61\uff0c\u4f46\u4e0d\u77e5\u9053\u5b83\u4f7f\u7528\u4e86\u54ea\u4e2a\u6784\u9020\u5668\uff08\u4f8b\u5982\u5b83\u6765\u81ea\u7b2c\u4e09\u65b9\u5e93\uff09\uff0c\u5e76\u4e14\u6211\u4eec\u9700\u8981\u521b\u5efa\u53e6\u4e00\u4e2a\u7c7b\u4f3c\u7684\u5bf9\u8c61\u65f6\uff0c\u7528\u8fd9\u79cd\u65b9\u6cd5\u5c31\u5f88\u65b9\u4fbf\u3002<br \/>\n\u4f46\u662f\uff0c\u5173\u4e8e &quot;constructor&quot; \u6700\u91cd\u8981\u7684\u662f\u2026\u2026<br \/>\n\u2026\u2026JavaScript \u81ea\u8eab\u5e76\u4e0d\u80fd\u786e\u4fdd\u6b63\u786e\u7684 &quot;constructor&quot; \u51fd\u6570\u503c\u3002<br \/>\n\u662f\u7684\uff0c\u5b83\u5b58\u5728\u4e8e\u51fd\u6570\u7684\u9ed8\u8ba4 &quot;prototype&quot; \u4e2d\uff0c\u4f46\u4ec5\u6b64\u800c\u5df2\u3002\u4e4b\u540e\u4f1a\u53d1\u751f\u4ec0\u4e48 \u2014\u2014 \u5b8c\u5168\u53d6\u51b3\u4e8e\u6211\u4eec\u3002<br \/>\n\u7279\u522b\u662f\uff0c\u5982\u679c\u6211\u4eec\u5c06\u6574\u4e2a\u9ed8\u8ba4 prototype \u66ff\u6362\u6389\uff0c\u90a3\u4e48\u5176\u4e2d\u5c31\u4e0d\u4f1a\u6709 &quot;constructor&quot; \u4e86\u3002<br \/>\n\u56e0\u6b64\uff0c\u4e3a\u4e86\u786e\u4fdd\u6b63\u786e\u7684\u00a0<code>&quot;constructor&quot;<\/code>\uff0c\u6211\u4eec\u53ef\u4ee5\u9009\u62e9\u6dfb\u52a0\/\u5220\u9664\u5c5e\u6027\u5230\u9ed8\u8ba4\u00a0<code>&quot;prototype&quot;<\/code>\uff0c\u800c\u4e0d\u662f\u5c06\u5176\u6574\u4e2a\u8986\u76d6<br \/>\n\u6216\u8005\uff0c\u4e5f\u53ef\u4ee5\u624b\u52a8\u91cd\u65b0\u521b\u5efa\u00a0<code>constructor<\/code>\u00a0\u5c5e\u6027<\/p>\n<h1>\u539f\u751f\u7684\u539f\u578b<\/h1>\n<p><code>&quot;prototype&quot;<\/code>\u00a0\u5c5e\u6027\u5728 JavaScript \u81ea\u8eab\u7684\u6838\u5fc3\u90e8\u5206\u4e2d\u88ab\u5e7f\u6cdb\u5730\u5e94\u7528\u3002\u6240\u6709\u7684\u5185\u5efa\u6784\u9020\u51fd\u6570\u90fd\u7528\u5230\u4e86\u5b83\u3002<br \/>\n\u9996\u5148\uff0c\u6211\u4eec\u5c06\u770b\u770b\u539f\u751f\u539f\u578b\u7684\u8be6\u7ec6\u4fe1\u606f\uff0c\u7136\u540e\u5b66\u4e60\u5982\u4f55\u4f7f\u7528\u5b83\u4e3a\u5185\u5efa\u5bf9\u8c61\u6dfb\u52a0\u65b0\u529f\u80fd\u3002<\/p>\n<h2>Object.prototype<\/h2>\n<pre><code class=\"language-js\">let obj = {};\nalert( obj ); \/\/ &quot;[object Object]&quot; ?\n<\/code><\/pre>\n<p>\u751f\u6210\u5b57\u7b26\u4e32 &quot;[object Object]&quot; \u7684\u4ee3\u7801\u5728\u54ea\u91cc\uff1f\u90a3\u5c31\u662f\u4e00\u4e2a\u5185\u5efa\u7684 toString \u65b9\u6cd5\uff0c\u4f46\u662f\u5b83\u5728\u54ea\u91cc\u5462\uff1fobj \u662f\u7a7a\u7684\uff01<br \/>\n\u2026\u2026\u7136\u800c\u7b80\u77ed\u7684\u8868\u8fbe\u5f0f obj = {} \u548c obj = new Object() \u662f\u4e00\u4e2a\u610f\u601d\uff0c\u5176\u4e2d Object \u5c31\u662f\u4e00\u4e2a\u5185\u5efa\u7684\u5bf9\u8c61\u6784\u9020\u51fd\u6570\uff0c\u5176\u81ea\u8eab\u7684 prototype \u6307\u5411\u4e00\u4e2a\u5e26\u6709 toString \u548c\u5176\u4ed6\u65b9\u6cd5\u7684\u4e00\u4e2a\u5de8\u5927\u7684\u5bf9\u8c61\u3002<br \/>\n\u6240\u4ee5\uff0c\u4e4b\u540e\u5f53\u00a0<code>obj.toString()<\/code>\u00a0\u88ab\u8c03\u7528\u65f6\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u662f\u4ece\u00a0<code>Object.prototype<\/code>\u00a0\u4e2d\u83b7\u53d6\u7684\u3002<br \/>\n\u8bf7\u6ce8\u610f\u5728\u00a0<code>Object.prototype<\/code>\u00a0\u4e0a\u65b9\u7684\u94fe\u4e2d\u6ca1\u6709\u66f4\u591a\u7684\u00a0<code>[[Prototype]]<\/code><\/p>\n<h2>\u5176\u4ed6\u5185\u5efa\u539f\u578b<\/h2>\n<p>\u5176\u4ed6\u5185\u5efa\u5bf9\u8c61\uff0c\u50cf\u00a0<code>Array<\/code>\u3001<code>Date<\/code>\u3001<code>Function<\/code>\u00a0\u53ca\u5176\u4ed6\uff0c\u90fd\u5728 prototype \u4e0a\u6302\u8f7d\u4e86\u65b9\u6cd5\u3002<br \/>\n\u4f8b\u5982\uff0c\u5f53\u6211\u4eec\u521b\u5efa\u4e00\u4e2a\u6570\u7ec4\u00a0<code>[1, 2, 3]<\/code>\uff0c\u5728\u5185\u90e8\u4f1a\u9ed8\u8ba4\u4f7f\u7528\u00a0<code>new Array()<\/code>\u00a0\u6784\u9020\u5668\u3002\u56e0\u6b64\u00a0<code>Array.prototype<\/code>\u00a0\u53d8\u6210\u4e86\u8fd9\u4e2a\u6570\u7ec4\u7684 prototype\uff0c\u5e76\u4e3a\u8fd9\u4e2a\u6570\u7ec4\u63d0\u4f9b\u6570\u7ec4\u7684\u64cd\u4f5c\u65b9\u6cd5\u3002\u8fd9\u6837\u5185\u5b58\u7684\u5b58\u50a8\u6548\u7387\u662f\u5f88\u9ad8\u7684\u3002<br \/>\n\u6309\u7167\u89c4\u8303\uff0c\u6240\u6709\u7684\u5185\u5efa\u539f\u578b\u9876\u7aef\u90fd\u662f\u00a0<code>Object.prototype<\/code>\u3002\u8fd9\u5c31\u662f\u4e3a\u4ec0\u4e48\u6709\u4eba\u8bf4\u201c\u4e00\u5207\u90fd\u4ece\u5bf9\u8c61\u7ee7\u627f\u800c\u6765\u201d\u3002<br \/>\n<div class='fancybox-wrapper lazyload-container-unload' data-fancybox='post-images' href='https:\/\/levin.ink\/wp-content\/uploads\/2024\/06\/Pasted-image-20240603141348.png'><img class=\"lazyload lazyload-style-1\" src=\"data:image\/svg+xml;base64,PCEtLUFyZ29uTG9hZGluZy0tPgo8c3ZnIHdpZHRoPSIxIiBoZWlnaHQ9IjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyIgc3Ryb2tlPSIjZmZmZmZmMDAiPjxnPjwvZz4KPC9zdmc+\"  decoding=\"async\" data-original=\"https:\/\/levin.ink\/wp-content\/uploads\/2024\/06\/Pasted-image-20240603141348.png\" src=\"data:image\/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB\/AAffA0nNPuCLAAAAAElFTkSuQmCC\" alt=\"Pasted image 20240603141348.png\"><\/div><br \/>\n\u4e00\u4e9b\u65b9\u6cd5\u5728\u539f\u578b\u4e0a\u53ef\u80fd\u4f1a\u53d1\u751f\u91cd\u53e0\uff0c\u4f8b\u5982\uff0c<code>Array.prototype<\/code>\u00a0\u6709\u81ea\u5df1\u7684\u00a0<code>toString<\/code>\u00a0\u65b9\u6cd5\u6765\u5217\u4e3e\u51fa\u6765\u6570\u7ec4\u7684\u6240\u6709\u5143\u7d20\u5e76\u7528\u9017\u53f7\u5206\u9694\u6bcf\u4e00\u4e2a\u5143\u7d20\u3002<br \/>\n\u6b63\u5982\u6211\u4eec\u4e4b\u524d\u770b\u5230\u7684\u90a3\u6837\uff0c<code>Object.prototype<\/code>\u00a0\u4e5f\u6709\u00a0<code>toString<\/code>\u00a0\u65b9\u6cd5\uff0c\u4f46\u662f\u00a0<code>Array.prototype<\/code>\u00a0\u5728\u539f\u578b\u94fe\u4e0a\u66f4\u8fd1\uff0c\u6240\u4ee5\u6570\u7ec4\u5bf9\u8c61\u539f\u578b\u4e0a\u7684\u65b9\u6cd5\u4f1a\u88ab\u4f7f\u7528\u3002<br \/>\n\u5176\u4ed6\u5185\u5efa\u5bf9\u8c61\u4e5f\u4ee5\u540c\u6837\u7684\u65b9\u5f0f\u8fd0\u884c\u3002\u5373\u4f7f\u662f\u51fd\u6570 \u2014\u2014 \u5b83\u4eec\u662f\u5185\u5efa\u6784\u9020\u5668\u00a0<code>Function<\/code>\u00a0\u7684\u5bf9\u8c61\uff0c\u5e76\u4e14\u5b83\u4eec\u7684\u65b9\u6cd5\uff08<code>call<\/code>\/<code>apply<\/code>\u00a0\u53ca\u5176\u4ed6\uff09\u90fd\u53d6\u81ea\u00a0<code>Function.prototype<\/code>\u3002\u51fd\u6570\u4e5f\u6709\u81ea\u5df1\u7684\u00a0<code>toString<\/code>\u00a0\u65b9\u6cd5\u3002<\/p>\n<h2>\u57fa\u672c\u6570\u636e\u7c7b\u578b<\/h2>\n<p>\u6700\u590d\u6742\u7684\u4e8b\u60c5\u53d1\u751f\u5728\u5b57\u7b26\u4e32\u3001\u6570\u5b57\u548c\u5e03\u5c14\u503c\u4e0a\u3002<br \/>\n\u6b63\u5982\u6211\u4eec\u8bb0\u5fc6\u4e2d\u7684\u90a3\u6837\uff0c\u5b83\u4eec\u5e76\u4e0d\u662f\u5bf9\u8c61\u3002\u4f46\u662f\u5982\u679c\u6211\u4eec\u8bd5\u56fe\u8bbf\u95ee\u5b83\u4eec\u7684\u5c5e\u6027\uff0c\u90a3\u4e48\u4e34\u65f6\u5305\u88c5\u5668\u5bf9\u8c61\u5c06\u4f1a\u901a\u8fc7\u5185\u5efa\u7684\u6784\u9020\u5668\u00a0<code>String<\/code>\u3001<code>Number<\/code>\u00a0\u548c\u00a0<code>Boolean<\/code>\u00a0\u88ab\u521b\u5efa\u3002\u5b83\u4eec\u63d0\u4f9b\u7ed9\u6211\u4eec\u64cd\u4f5c\u5b57\u7b26\u4e32\u3001\u6570\u5b57\u548c\u5e03\u5c14\u503c\u7684\u65b9\u6cd5\u7136\u540e\u6d88\u5931\u3002<br \/>\n\u8fd9\u4e9b\u5bf9\u8c61\u5bf9\u6211\u4eec\u6765\u8bf4\u662f\u65e0\u5f62\u5730\u521b\u5efa\u51fa\u6765\u7684\u3002\u5927\u591a\u6570\u5f15\u64ce\u90fd\u4f1a\u5bf9\u5176\u8fdb\u884c\u4f18\u5316\uff0c\u4f46\u662f\u89c4\u8303\u4e2d\u63cf\u8ff0\u7684\u5c31\u662f\u901a\u8fc7\u8fd9\u79cd\u65b9\u5f0f\u3002\u8fd9\u4e9b\u5bf9\u8c61\u7684\u65b9\u6cd5\u4e5f\u9a7b\u7559\u5728\u5b83\u4eec\u7684 prototype \u4e2d\uff0c\u53ef\u4ee5\u901a\u8fc7\u00a0<code>String.prototype<\/code>\u3001<code>Number.prototype<\/code>\u00a0\u548c\u00a0<code>Boolean.prototype<\/code>\u00a0\u8fdb\u884c\u83b7\u53d6\u3002<\/p>\n<blockquote>\n<p>\u503c\u00a0<code>null<\/code>\u00a0\u548c\u00a0<code>undefined<\/code>\u00a0\u6ca1\u6709\u5bf9\u8c61\u5305\u88c5\u5668<br \/>\n\u7279\u6b8a\u503c\u00a0<code>null<\/code>\u00a0\u548c\u00a0<code>undefined<\/code>\u00a0\u6bd4\u8f83\u7279\u6b8a\u3002\u5b83\u4eec\u6ca1\u6709\u5bf9\u8c61\u5305\u88c5\u5668\uff0c\u6240\u4ee5\u5b83\u4eec\u6ca1\u6709\u65b9\u6cd5\u548c\u5c5e\u6027\u3002\u5e76\u4e14\u5b83\u4eec\u4e5f\u6ca1\u6709\u76f8\u5e94\u7684\u539f\u578b\u3002<\/p>\n<\/blockquote>\n<h2>\u66f4\u6539\u539f\u751f\u7c7b\u578b<\/h2>\n<p>\u539f\u751f\u7684\u539f\u578b\u662f\u53ef\u4ee5\u88ab\u4fee\u6539\u7684\u3002\u4f8b\u5982\uff0c\u6211\u4eec\u5411\u00a0<code>String.prototype<\/code>\u00a0\u4e2d\u6dfb\u52a0\u4e00\u4e2a\u65b9\u6cd5\uff0c\u8fd9\u4e2a\u65b9\u6cd5\u5c06\u5bf9\u6240\u6709\u7684\u5b57\u7b26\u4e32\u90fd\u662f\u53ef\u7528\u7684\uff1a<\/p>\n<pre><code class=\"language-js\">String.prototype.show = function() {\n  alert(this);\n};\n\n&quot;BOOM!&quot;.show(); \/\/ BOOM!\n<\/code><\/pre>\n<p>\u5728\u5f00\u53d1\u7684\u8fc7\u7a0b\u4e2d\uff0c\u6211\u4eec\u53ef\u80fd\u4f1a\u60f3\u8981\u4e00\u4e9b\u65b0\u7684\u5185\u5efa\u65b9\u6cd5\uff0c\u5e76\u4e14\u60f3\u628a\u5b83\u4eec\u6dfb\u52a0\u5230\u539f\u751f\u539f\u578b\u4e2d\u3002\u4f46\u8fd9\u901a\u5e38\u662f\u4e00\u4e2a\u5f88\u4e0d\u597d\u7684\u60f3\u6cd5\u3002<\/p>\n<blockquote>\n<p>\u91cd\u8981\uff1a<br \/>\n\u539f\u578b\u662f\u5168\u5c40\u7684\uff0c\u6240\u4ee5\u5f88\u5bb9\u6613\u9020\u6210\u51b2\u7a81\u3002\u5982\u679c\u6709\u4e24\u4e2a\u5e93\u90fd\u6dfb\u52a0\u4e86\u00a0<code>String.prototype.show<\/code>\u00a0\u65b9\u6cd5\uff0c\u90a3\u4e48\u5176\u4e2d\u7684\u4e00\u4e2a\u65b9\u6cd5\u5c06\u88ab\u53e6\u4e00\u4e2a\u8986\u76d6\u3002<br \/>\n\u6240\u4ee5\uff0c\u901a\u5e38\u6765\u8bf4\uff0c\u4fee\u6539\u539f\u751f\u539f\u578b\u88ab\u8ba4\u4e3a\u662f\u4e00\u4e2a\u5f88\u4e0d\u597d\u7684\u60f3\u6cd5\u3002<\/p>\n<\/blockquote>\n<p>\u5728\u73b0\u4ee3\u7f16\u7a0b\u4e2d\uff0c\u53ea\u6709\u4e00\u79cd\u60c5\u51b5\u4e0b\u5141\u8bb8\u4fee\u6539\u539f\u751f\u539f\u578b\u3002\u90a3\u5c31\u662f polyfilling\u3002<br \/>\nPolyfilling \u662f\u4e00\u4e2a\u672f\u8bed\uff0c\u8868\u793a\u67d0\u4e2a\u65b9\u6cd5\u5728 JavaScript \u89c4\u8303\u4e2d\u5df2\u5b58\u5728\uff0c\u4f46\u662f\u7279\u5b9a\u7684 JavaScript \u5f15\u64ce\u5c1a\u4e0d\u652f\u6301\u8be5\u65b9\u6cd5\uff0c\u90a3\u4e48\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u624b\u52a8\u5b9e\u73b0\u5b83\uff0c\u5e76\u7528\u4ee5\u586b\u5145\u5185\u5efa\u539f\u578b\u3002<\/p>\n<h2>\u4ece\u539f\u578b\u4e2d\u501f\u7528<\/h2>\n<p>\u5728\u00a0<a href=\"https:\/\/zh.javascript.info\/call-apply-decorators#method-borrowing\">\u88c5\u9970\u5668\u6a21\u5f0f\u548c\u8f6c\u53d1\uff0ccall\/apply<\/a>\u00a0\u4e00\u7ae0\u4e2d\uff0c\u6211\u4eec\u8ba8\u8bba\u4e86\u65b9\u6cd5\u501f\u7528\u3002<br \/>\n\u90a3\u662f\u6307\u6211\u4eec\u4ece\u4e00\u4e2a\u5bf9\u8c61\u83b7\u53d6\u4e00\u4e2a\u65b9\u6cd5\uff0c\u5e76\u5c06\u5176\u590d\u5236\u5230\u53e6\u4e00\u4e2a\u5bf9\u8c61\u3002<br \/>\n\u4e00\u4e9b\u539f\u751f\u539f\u578b\u7684\u65b9\u6cd5\u901a\u5e38\u4f1a\u88ab\u501f\u7528\u3002<br \/>\n\u4f8b\u5982\uff0c\u5982\u679c\u6211\u4eec\u8981\u521b\u5efa\u7c7b\u6570\u7ec4\u5bf9\u8c61\uff0c\u5219\u53ef\u80fd\u9700\u8981\u5411\u5176\u4e2d\u590d\u5236\u4e00\u4e9b\u00a0<code>Array<\/code>\u00a0\u65b9\u6cd5\u3002<\/p>\n<pre><code class=\"language-js\">let obj = {\n  0: &quot;Hello&quot;,\n  1: &quot;world!&quot;,\n  length: 2,\n};\n\nobj.join = Array.prototype.join;\n\nalert( obj.join(',') ); \/\/ Hello,world!\n<\/code><\/pre>\n<p>\u4e0a\u9762\u8fd9\u6bb5\u4ee3\u7801\u6709\u6548\uff0c\u662f\u56e0\u4e3a\u5185\u5efa\u7684\u65b9\u6cd5\u00a0<code>join<\/code>\u00a0\u7684\u5185\u90e8\u7b97\u6cd5\u53ea\u5173\u5fc3\u6b63\u786e\u7684\u7d22\u5f15\u548c\u00a0<code>length<\/code>\u00a0\u5c5e\u6027\u3002\u5b83\u4e0d\u4f1a\u68c0\u67e5\u8fd9\u4e2a\u5bf9\u8c61\u662f\u5426\u662f\u771f\u6b63\u7684\u6570\u7ec4\u3002\u8bb8\u591a\u5185\u5efa\u65b9\u6cd5\u5c31\u662f\u8fd9\u6837\u3002<br \/>\n\u53e6\u4e00\u79cd\u65b9\u5f0f\u662f\u901a\u8fc7\u5c06\u00a0<code>obj.__proto__<\/code>\u00a0\u8bbe\u7f6e\u4e3a\u00a0<code>Array.prototype<\/code>\uff0c\u8fd9\u6837\u00a0<code>Array<\/code>\u00a0\u4e2d\u7684\u6240\u6709\u65b9\u6cd5\u90fd\u81ea\u52a8\u5730\u53ef\u4ee5\u5728\u00a0<code>obj<\/code>\u00a0\u4e2d\u4f7f\u7528\u4e86\u3002<br \/>\n\u4f46\u662f\u5982\u679c\u00a0<code>obj<\/code>\u00a0\u5df2\u7ecf\u4ece\u53e6\u4e00\u4e2a\u5bf9\u8c61\u8fdb\u884c\u4e86\u7ee7\u627f\uff0c\u90a3\u4e48\u8fd9\u79cd\u65b9\u6cd5\u5c31\u4e0d\u53ef\u884c\u4e86\uff08\u8bd1\u6ce8\uff1a\u56e0\u4e3a\u8fd9\u6837\u4f1a\u8986\u76d6\u6389\u5df2\u6709\u7684\u7ee7\u627f\u3002\u6b64\u5904\u00a0<code>obj<\/code>\u00a0\u5176\u5b9e\u5df2\u7ecf\u4ece\u00a0<code>Object<\/code>\u00a0\u8fdb\u884c\u4e86\u7ee7\u627f\uff0c\u4f46\u662f\u00a0<code>Array<\/code>\u00a0\u4e5f\u7ee7\u627f\u81ea\u00a0<code>Object<\/code>\uff0c\u6240\u4ee5\u6b64\u5904\u7684\u65b9\u6cd5\u501f\u7528\u4e0d\u4f1a\u5f71\u54cd\u00a0<code>obj<\/code>\u00a0\u5bf9\u539f\u6709\u7ee7\u627f\u7684\u7ee7\u627f\uff0c\u56e0\u4e3a\u00a0<code>obj<\/code>\u00a0\u901a\u8fc7\u539f\u578b\u94fe\u4f9d\u65e7\u7ee7\u627f\u4e86\u00a0<code>Object<\/code>\uff09\u3002\u8bf7\u8bb0\u4f4f\uff0c\u6211\u4eec\u4e00\u6b21\u53ea\u80fd\u7ee7\u627f\u4e00\u4e2a\u5bf9\u8c61\u3002<br \/>\n\u65b9\u6cd5\u501f\u7528\u5f88\u7075\u6d3b\uff0c\u5b83\u5141\u8bb8\u5728\u9700\u8981\u65f6\u6df7\u5408\u6765\u81ea\u4e0d\u540c\u5bf9\u8c61\u7684\u65b9\u6cd5\u3002<\/p>\n<h1>\u539f\u578b\u65b9\u6cd5\uff0c\u6ca1\u6709__proto__\u7684\u5bf9\u8c61<\/h1>\n<p>\u5728\u8fd9\u90e8\u5206\u5185\u5bb9\u7684\u7b2c\u4e00\u7ae0\u4e2d\uff0c\u6211\u4eec\u63d0\u5230\u4e86\u8bbe\u7f6e\u539f\u578b\u7684\u73b0\u4ee3\u65b9\u6cd5\u3002<br \/>\n\u4f7f\u7528\u00a0<code>obj.__proto__<\/code>\u00a0\u8bbe\u7f6e\u6216\u8bfb\u53d6\u539f\u578b\u88ab\u8ba4\u4e3a\u5df2\u7ecf\u8fc7\u65f6\u4e14\u4e0d\u63a8\u8350\u4f7f\u7528\uff08deprecated\uff09\u4e86\uff08\u5df2\u7ecf\u88ab\u79fb\u81f3 JavaScript \u89c4\u8303\u7684\u9644\u5f55 B\uff0c\u610f\u5473\u7740\u4ec5\u9002\u7528\u4e8e\u6d4f\u89c8\u5668\uff09\u3002<br \/>\n\u73b0\u4ee3\u7684\u83b7\u53d6\/\u8bbe\u7f6e\u539f\u578b\u7684\u65b9\u6cd5\u6709\uff1a<\/p>\n<ul>\n<li><a href=\"https:\/\/developer.mozilla.org\/zh\/docs\/Web\/JavaScript\/Reference\/Global_Objects\/Object\/getPrototypeOf\">Object.getPrototypeOf(obj)<\/a>\u00a0\u2014\u2014 \u8fd4\u56de\u5bf9\u8c61\u00a0<code>obj<\/code>\u00a0\u7684\u00a0<code>[[Prototype]]<\/code>\u3002<\/li>\n<li><a href=\"https:\/\/developer.mozilla.org\/zh\/docs\/Web\/JavaScript\/Reference\/Global_Objects\/Object\/setPrototypeOf\">Object.setPrototypeOf(obj, proto)<\/a>\u00a0\u2014\u2014 \u5c06\u5bf9\u8c61\u00a0<code>obj<\/code>\u00a0\u7684\u00a0<code>[[Prototype]]<\/code>\u00a0\u8bbe\u7f6e\u4e3a\u00a0<code>proto<\/code>\u3002<br \/>\n<code>__proto__<\/code>\u00a0\u4e0d\u88ab\u53cd\u5bf9\u7684\u552f\u4e00\u7684\u7528\u6cd5\u662f\u5728\u521b\u5efa\u65b0\u5bf9\u8c61\u65f6\uff0c\u5c06\u5176\u7528\u4f5c\u5c5e\u6027\uff1a<code>{ __proto__: ... }<\/code>\u3002<br \/>\n\u867d\u7136\uff0c\u4e5f\u6709\u4e00\u79cd\u7279\u6b8a\u7684\u65b9\u6cd5\uff1a<\/li>\n<li><a href=\"https:\/\/developer.mozilla.org\/zh\/docs\/Web\/JavaScript\/Reference\/Global_Objects\/Object\/create\">Object.create(proto, [descriptors])<\/a>\u00a0\u2014\u2014 \u5229\u7528\u7ed9\u5b9a\u7684\u00a0<code>proto<\/code>\u00a0\u4f5c\u4e3a\u00a0<code>[[Prototype]]<\/code>\u00a0\u548c\u53ef\u9009\u7684\u5c5e\u6027\u63cf\u8ff0\u6765\u521b\u5efa\u4e00\u4e2a\u7a7a\u5bf9\u8c61\u3002<\/li>\n<\/ul>\n<pre><code class=\"language-js\">let animal = {\n  eats: true\n};\n\n\/\/ \u521b\u5efa\u4e00\u4e2a\u4ee5 animal \u4e3a\u539f\u578b\u7684\u65b0\u5bf9\u8c61\nlet rabbit = Object.create(animal); \/\/ \u4e0e {__proto__: animal} \u76f8\u540c\n\nalert(rabbit.eats); \/\/ true\n\nalert(Object.getPrototypeOf(rabbit) === animal); \/\/ true\n\nObject.setPrototypeOf(rabbit, {}); \/\/ \u5c06 rabbit \u7684\u539f\u578b\u4fee\u6539\u4e3a {}\n<\/code><\/pre>\n<p><code>Object.create<\/code>\u00a0\u65b9\u6cd5\u66f4\u5f3a\u5927\uff0c\u56e0\u4e3a\u5b83\u6709\u4e00\u4e2a\u53ef\u9009\u7684\u7b2c\u4e8c\u53c2\u6570\uff1a\u5c5e\u6027\u63cf\u8ff0\u5668\u3002<br \/>\n\u6211\u4eec\u53ef\u4ee5\u5728\u6b64\u5904\u4e3a\u65b0\u5bf9\u8c61\u63d0\u4f9b\u989d\u5916\u7684\u5c5e\u6027\uff0c\u5c31\u50cf\u8fd9\u6837\uff1a<\/p>\n<pre><code class=\"language-js\">let animal = {\n  eats: true\n};\n\nlet rabbit = Object.create(animal, {\n  jumps: {\n    value: true\n  }\n});\n\nalert(rabbit.jumps); \/\/ true\n<\/code><\/pre>\n<p>\u63cf\u8ff0\u5668\u7684\u683c\u5f0f\u4e0e\u00a0<a href=\"https:\/\/zh.javascript.info\/property-descriptors\">\u5c5e\u6027\u6807\u5fd7\u548c\u5c5e\u6027\u63cf\u8ff0\u7b26<\/a>\u00a0\u4e00\u7ae0\u4e2d\u6240\u8bb2\u7684\u4e00\u6837\u3002<br \/>\n\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u00a0<code>Object.create<\/code>\u00a0\u6765\u5b9e\u73b0\u6bd4\u590d\u5236\u00a0<code>for..in<\/code>\u00a0\u5faa\u73af\u4e2d\u7684\u5c5e\u6027\u66f4\u5f3a\u5927\u7684\u5bf9\u8c61\u514b\u9686\u65b9\u5f0f<\/p>\n<pre><code class=\"language-js\">let clone = Object.create(\n  Object.getPrototypeOf(obj),\n  Object.getOwnPropertyDescriptors(obj)\n);\n<\/code><\/pre>\n<p>\u6b64\u8c03\u7528\u53ef\u4ee5\u5bf9 obj \u8fdb\u884c\u771f\u6b63\u51c6\u786e\u5730\u62f7\u8d1d\uff0c\u5305\u62ec\u6240\u6709\u7684\u5c5e\u6027\uff1a\u53ef\u679a\u4e3e\u548c\u4e0d\u53ef\u679a\u4e3e\u7684\uff0c\u6570\u636e\u5c5e\u6027\u548c setters\/getters \u2014\u2014 \u5305\u62ec\u6240\u6709\u5185\u5bb9\uff0c\u5e76\u5e26\u6709\u6b63\u786e\u7684 [[Prototype]]\u3002<\/p>\n<h2>\u539f\u578b\u7b80\u53f2<\/h2>\n<p>\u6709\u8fd9\u4e48\u591a\u53ef\u4ee5\u5904\u7406\u00a0<code>[[Prototype]]<\/code>\u00a0\u7684\u65b9\u5f0f\u3002\u53d1\u751f\u4e86\u4ec0\u4e48\uff1f\u4e3a\u4ec0\u4e48\u4f1a\u8fd9\u6837\uff1f<br \/>\n\u8fd9\u662f\u5386\u53f2\u539f\u56e0\u3002<br \/>\n\u539f\u578b\u7ee7\u627f\u4ece\u4e00\u5f00\u59cb\u5c31\u5b58\u5728\u4e8e\u8bed\u8a00\u4e2d\uff0c\u4f46\u7ba1\u7406\u5b83\u7684\u65b9\u5f0f\u968f\u7740\u65f6\u95f4\u7684\u63a8\u79fb\u800c\u6f14\u53d8\u3002<\/p>\n<ul>\n<li>\u6784\u9020\u51fd\u6570\u7684\u00a0<code>&quot;prototype&quot;<\/code>\u00a0\u5c5e\u6027\u81ea\u53e4\u4ee5\u6765\u5c31\u8d77\u4f5c\u7528\u3002\u8fd9\u662f\u4f7f\u7528\u7ed9\u5b9a\u539f\u578b\u521b\u5efa\u5bf9\u8c61\u7684\u6700\u53e4\u8001\u7684\u65b9\u5f0f\u3002<\/li>\n<li>\u4e4b\u540e\uff0c\u5728 2012 \u5e74\uff0c<code>Object.create<\/code>\u00a0\u51fa\u73b0\u5728\u6807\u51c6\u4e2d\u3002\u5b83\u63d0\u4f9b\u4e86\u4f7f\u7528\u7ed9\u5b9a\u539f\u578b\u521b\u5efa\u5bf9\u8c61\u7684\u80fd\u529b\u3002\u4f46\u6ca1\u6709\u63d0\u4f9b get\/set \u5b83\u7684\u80fd\u529b\u3002\u4e00\u4e9b\u6d4f\u89c8\u5668\u5b9e\u73b0\u4e86\u975e\u6807\u51c6\u7684\u00a0<code>__proto__<\/code>\u00a0\u8bbf\u95ee\u5668\uff0c\u4ee5\u4e3a\u5f00\u53d1\u8005\u63d0\u4f9b\u66f4\u591a\u7684\u7075\u6d3b\u6027\u3002<\/li>\n<li>\u4e4b\u540e\uff0c\u5728 2015 \u5e74\uff0c<code>Object.setPrototypeOf<\/code>\u00a0\u548c\u00a0<code>Object.getPrototypeOf<\/code>\u00a0\u88ab\u52a0\u5165\u5230\u6807\u51c6\u4e2d\uff0c\u6267\u884c\u4e0e\u00a0<code>__proto__<\/code>\u00a0\u76f8\u540c\u7684\u529f\u80fd\u3002\u7531\u4e8e\u00a0<code>__proto__<\/code>\u00a0\u5b9e\u9645\u4e0a\u5df2\u7ecf\u5728\u6240\u6709\u5730\u65b9\u90fd\u5f97\u5230\u4e86\u5b9e\u73b0\uff0c\u4f46\u5b83\u5df2\u8fc7\u65f6\uff0c\u6240\u4ee5\u88ab\u52a0\u5165\u5230\u8be5\u6807\u51c6\u7684\u9644\u4ef6 B \u4e2d\uff0c\u5373\uff1a\u5728\u975e\u6d4f\u89c8\u5668\u73af\u5883\u4e0b\uff0c\u5b83\u7684\u652f\u6301\u662f\u53ef\u9009\u7684\u3002<\/li>\n<li>\u4e4b\u540e\uff0c\u5728 2022 \u5e74\uff0c\u5b98\u65b9\u5141\u8bb8\u5728\u5bf9\u8c61\u5b57\u9762\u91cf\u00a0<code>{...}<\/code>\u00a0\u4e2d\u4f7f\u7528\u00a0<code>__proto__<\/code>\uff08\u4ece\u9644\u5f55 B \u4e2d\u79fb\u51fa\u6765\u4e86\uff09\uff0c\u4f46\u4e0d\u80fd\u7528\u4f5c getter\/setter\u00a0<code>obj.__proto__<\/code>\uff08\u4ecd\u5728\u9644\u5f55 B \u4e2d\uff09\u3002<br \/>\n\u4e3a\u4ec0\u4e48\u8981\u7528\u51fd\u6570\u00a0<code>getPrototypeOf\/setPrototypeOf<\/code>\u00a0\u53d6\u4ee3\u00a0<code>__proto__<\/code>\uff1f<br \/>\n\u4e3a\u4ec0\u4e48\u00a0<code>__proto__<\/code>\u00a0\u88ab\u90e8\u5206\u8ba4\u53ef\u5e76\u5141\u8bb8\u5728\u00a0<code>{...}<\/code>\u00a0\u4e2d\u4f7f\u7528\uff0c\u4f46\u4ecd\u4e0d\u80fd\u7528\u4f5c getter\/setter\uff1f<br \/>\n\u8fd9\u662f\u4e00\u4e2a\u6709\u8da3\u7684\u95ee\u9898\uff0c\u9700\u8981\u6211\u4eec\u7406\u89e3\u4e3a\u4ec0\u4e48\u00a0<code>__proto__<\/code>\u00a0\u4e0d\u597d\u3002<br \/>\n\u5f88\u5feb\u6211\u4eec\u5c31\u4f1a\u770b\u5230\u7b54\u6848\u3002<\/li>\n<\/ul>\n<blockquote>\n<p>\u5982\u679c\u901f\u5ea6\u5f88\u91cd\u8981\uff0c\u5c31\u8bf7\u4e0d\u8981\u4fee\u6539\u5df2\u5b58\u5728\u7684\u5bf9\u8c61\u7684\u00a0<code>[[Prototype]]<\/code><br \/>\n\u4ece\u6280\u672f\u4e0a\u6765\u8bb2\uff0c\u6211\u4eec\u53ef\u4ee5\u5728\u4efb\u4f55\u65f6\u5019 get\/set\u00a0<code>[[Prototype]]<\/code>\u3002\u4f46\u662f\u901a\u5e38\u6211\u4eec\u53ea\u5728\u521b\u5efa\u5bf9\u8c61\u7684\u65f6\u5019\u8bbe\u7f6e\u5b83\u4e00\u6b21\uff0c\u81ea\u90a3\u4e4b\u540e\u4e0d\u518d\u4fee\u6539\uff1a<code>rabbit<\/code>\u00a0\u7ee7\u627f\u81ea\u00a0<code>animal<\/code>\uff0c\u4e4b\u540e\u4e0d\u518d\u66f4\u6539\u3002<br \/>\n\u5e76\u4e14\uff0cJavaScript \u5f15\u64ce\u5bf9\u6b64\u8fdb\u884c\u4e86\u9ad8\u5ea6\u4f18\u5316\u3002\u7528\u00a0<code>Object.setPrototypeOf<\/code>\u00a0\u6216\u00a0<code>obj.__proto__=<\/code>\u00a0\u201c\u5373\u65f6\u201d\u66f4\u6539\u539f\u578b\u662f\u4e00\u4e2a\u975e\u5e38\u7f13\u6162\u7684\u64cd\u4f5c\uff0c\u56e0\u4e3a\u5b83\u7834\u574f\u4e86\u5bf9\u8c61\u5c5e\u6027\u8bbf\u95ee\u64cd\u4f5c\u7684\u5185\u90e8\u4f18\u5316\u3002\u56e0\u6b64\uff0c\u9664\u975e\u4f60\u77e5\u9053\u81ea\u5df1\u5728\u505a\u4ec0\u4e48\uff0c\u6216\u8005 JavaScript \u7684\u6267\u884c\u901f\u5ea6\u5bf9\u4f60\u6765\u8bf4\u5b8c\u5168\u4e0d\u91cd\u8981\uff0c\u5426\u5219\u8bf7\u907f\u514d\u4f7f\u7528\u5b83\u3002<\/p>\n<\/blockquote>\n<h2>Very plain objects<\/h2>\n<p>\u6211\u4eec\u77e5\u9053\uff0c\u5bf9\u8c61\u53ef\u4ee5\u7528\u4f5c\u5173\u8054\u6570\u7ec4\uff08associative arrays\uff09\u6765\u5b58\u50a8\u952e\/\u503c\u5bf9\u3002<br \/>\n\u2026\u2026\u4f46\u662f\u5982\u679c\u6211\u4eec\u5c1d\u8bd5\u5728\u5176\u4e2d\u5b58\u50a8\u00a0<strong>\u7528\u6237\u63d0\u4f9b\u7684<\/strong>\u00a0\u952e\uff08\u4f8b\u5982\uff1a\u4e00\u4e2a\u7528\u6237\u8f93\u5165\u7684\u5b57\u5178\uff09\uff0c\u6211\u4eec\u53ef\u4ee5\u53d1\u73b0\u4e00\u4e2a\u6709\u8da3\u7684\u5c0f\u6545\u969c\uff1a\u6240\u6709\u7684\u952e\u90fd\u6b63\u5e38\u5de5\u4f5c\uff0c\u9664\u4e86\u00a0<code>&quot;__proto__&quot;<\/code>\u3002<\/p>\n<pre><code class=\"language-js\">let obj = {};\n\nlet key = prompt(&quot;What's the key?&quot;, &quot;__proto__&quot;);\nobj[key] = &quot;some value&quot;;\n\nalert(obj[key]); \/\/ [object Object]\uff0c\u5e76\u4e0d\u662f &quot;some value&quot;\uff01\n<\/code><\/pre>\n<p>\u8fd9\u91cc\u5982\u679c\u7528\u6237\u8f93\u5165 <strong>proto<\/strong>\uff0c\u90a3\u4e48\u5728\u7b2c\u56db\u884c\u7684\u8d4b\u503c\u4f1a\u88ab\u5ffd\u7565\uff01<br \/>\n\u5bf9\u4e8e\u975e\u5f00\u53d1\u8005\u6765\u8bf4\uff0c\u8fd9\u80af\u5b9a\u5f88\u4ee4\u4eba\u60ca\u8bb6\uff0c\u4f46\u5bf9\u6211\u4eec\u6765\u8bf4\u5374\u662f\u53ef\u4ee5\u7406\u89e3\u7684\u3002<strong>proto<\/strong> \u5c5e\u6027\u5f88\u7279\u6b8a\uff1a\u5b83\u5fc5\u987b\u662f\u4e00\u4e2a\u5bf9\u8c61\u6216\u8005 null\u3002\u5b57\u7b26\u4e32\u4e0d\u80fd\u6210\u4e3a\u539f\u578b\u3002\u8fd9\u5c31\u662f\u4e3a\u4ec0\u4e48\u5c06\u5b57\u7b26\u4e32\u8d4b\u503c\u7ed9 <strong>proto<\/strong> \u4f1a\u88ab\u5ffd\u7565\u3002<br \/>\n\u4f46\u6211\u4eec\u4e0d\u662f \u6253\u7b97 \u5b9e\u73b0\u8fd9\u79cd\u884c\u4e3a\uff0c\u5bf9\u5427\uff1f\u6211\u4eec\u60f3\u8981\u5b58\u50a8\u952e\u503c\u5bf9\uff0c\u7136\u800c\u952e\u540d\u4e3a &quot;<strong>proto<\/strong>&quot; \u7684\u952e\u503c\u5bf9\u6ca1\u6709\u88ab\u6b63\u786e\u5b58\u50a8\u3002\u6240\u4ee5\u8fd9\u662f\u4e00\u4e2a bug\u3002<br \/>\n\u8fd9\u91cc\u7684\u540e\u679c\u5e76\u6ca1\u6709\u5f88\u4e25\u91cd\u3002\u4f46\u5728\u5176\u4ed6\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u53ef\u80fd\u4f1a\u5728 obj \u4e2d\u5b58\u50a8\u5bf9\u8c61\u800c\u4e0d\u662f\u5b57\u7b26\u4e32\uff0c\u5219\u539f\u578b\u786e\u5b9e\u4f1a\u88ab\u6539\u53d8\u3002\u7ed3\u679c\uff0c\u6267\u884c\u5c06\u4ee5\u5b8c\u5168\u610f\u60f3\u4e0d\u5230\u7684\u65b9\u5f0f\u51fa\u9519\u3002<br \/>\n\u6700\u53ef\u6015\u7684\u662f \u2014\u2014 \u901a\u5e38\u5f00\u53d1\u8005\u5b8c\u5168\u4e0d\u4f1a\u8003\u8651\u5230\u8fd9\u4e00\u70b9\u3002\u8fd9\u8ba9\u6b64\u7c7b bug \u5f88\u96be\u88ab\u53d1\u73b0\uff0c\u751a\u81f3\u53d8\u6210\u6f0f\u6d1e\uff0c\u5c24\u5176\u662f\u5728 JavaScript \u88ab\u7528\u5728\u670d\u52a1\u7aef\u7684\u65f6\u5019\u3002<br \/>\n\u5bf9 obj.toString \u8fdb\u884c\u8d4b\u503c\u65f6\u4e5f\u53ef\u80fd\u53d1\u751f\u610f\u60f3\u4e0d\u5230\u7684\u4e8b\u60c5\uff0c\u56e0\u4e3a\u5b83\u662f\u4e00\u4e2a\u5185\u5efa\u7684\u5bf9\u8c61\u65b9\u6cd5\u3002<br \/>\n\u6211\u4eec\u600e\u4e48\u907f\u514d\u8fd9\u6837\u7684\u95ee\u9898\u5462\uff1f<br \/>\n\u9996\u5148\uff0c\u6211\u4eec\u53ef\u4ee5\u6539\u7528 Map \u6765\u4ee3\u66ff\u666e\u901a\u5bf9\u8c61\u8fdb\u884c\u5b58\u50a8\uff0c\u8fd9\u6837\u4e00\u5207\u90fd\u8fce\u5203\u800c\u89e3<\/p>\n<pre><code class=\"language-js\">let map = new Map();\n\nlet key = prompt(&quot;What's the key?&quot;, &quot;__proto__&quot;);\nmap.set(key, &quot;some value&quot;);\n\nalert(map.get(key)); \/\/ &quot;some value&quot;\uff08\u7b26\u5408\u9884\u671f\uff09\n<\/code><\/pre>\n<p>\u2026\u2026\u4f46 Object \u8bed\u6cd5\u901a\u5e38\u66f4\u5438\u5f15\u4eba\uff0c\u56e0\u4e3a\u5b83\u66f4\u7b80\u6d01\u3002<br \/>\n\u5e78\u8fd0\u7684\u662f\uff0c\u6211\u4eec \u53ef\u4ee5 \u4f7f\u7528\u5bf9\u8c61\uff0c\u56e0\u4e3a JavaScript \u8bed\u8a00\u7684\u5236\u9020\u8005\u5f88\u4e45\u4ee5\u524d\u5c31\u8003\u8651\u8fc7\u8fd9\u4e2a\u95ee\u9898\u3002<br \/>\n\u6b63\u5982\u6211\u4eec\u6240\u77e5\u9053\u7684\uff0c<strong>proto<\/strong> \u4e0d\u662f\u5bf9\u8c61\u7684\u5c5e\u6027\uff0c\u800c\u662f Object.prototype \u7684\u8bbf\u95ee\u5668\u5c5e\u6027<br \/>\n\u56e0\u6b64\uff0c\u5982\u679c\u00a0<code>obj.__proto__<\/code>\u00a0\u88ab\u8bfb\u53d6\u6216\u8005\u8d4b\u503c\uff0c\u90a3\u4e48\u5bf9\u5e94\u7684 getter\/setter \u4f1a\u88ab\u4ece\u5b83\u7684\u539f\u578b\u4e2d\u8c03\u7528\uff0c\u5b83\u4f1a set\/get\u00a0<code>[[Prototype]]<\/code>\u3002<br \/>\n\u5c31\u50cf\u5728\u672c\u90e8\u5206\u6559\u7a0b\u7684\u5f00\u5934\u6240\u8bf4\u7684\u90a3\u6837\uff1a<code>__proto__<\/code>\u00a0\u662f\u4e00\u79cd\u8bbf\u95ee\u00a0<code>[[Prototype]]<\/code>\u00a0\u7684\u65b9\u5f0f\uff0c\u800c\u4e0d\u662f\u00a0<code>[[prototype]]<\/code>\u00a0\u672c\u8eab\u3002<br \/>\n\u73b0\u5728\uff0c\u6211\u4eec\u60f3\u8981\u5c06\u4e00\u4e2a\u5bf9\u8c61\u7528\u4f5c\u5173\u8054\u6570\u7ec4\uff0c\u5e76\u4e14\u6446\u8131\u6b64\u7c7b\u95ee\u9898\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u4e00\u4e9b\u5c0f\u6280\u5de7<\/p>\n<pre><code class=\"language-js\">let obj = Object.create(null);\n\/\/ \u6216\u8005\uff1aobj = { __proto__: null }\n\nlet key = prompt(&quot;What's the key?&quot;, &quot;__proto__&quot;);\nobj[key] = &quot;some value&quot;;\n\nalert(obj[key]); \/\/ &quot;some value&quot;\n<\/code><\/pre>\n<p><code>Object.create(null)<\/code>\u00a0\u521b\u5efa\u4e86\u4e00\u4e2a\u7a7a\u5bf9\u8c61\uff0c\u8fd9\u4e2a\u5bf9\u8c61\u6ca1\u6709\u539f\u578b\uff08<code>[[Prototype]]<\/code>\u00a0\u662f\u00a0<code>null<\/code>\uff09\uff1a<br \/>\n\u56e0\u6b64\uff0c\u5b83\u6ca1\u6709\u7ee7\u627f\u00a0<code>__proto__<\/code>\u00a0\u7684 getter\/setter \u65b9\u6cd5\u3002\u73b0\u5728\uff0c\u5b83\u88ab\u4f5c\u4e3a\u6b63\u5e38\u7684\u6570\u636e\u5c5e\u6027\u8fdb\u884c\u5904\u7406\uff0c\u56e0\u6b64\u4e0a\u9762\u7684\u8fd9\u4e2a\u793a\u4f8b\u80fd\u591f\u6b63\u5e38\u5de5\u4f5c\u3002<br \/>\n\u6211\u4eec\u53ef\u4ee5\u628a\u8fd9\u6837\u7684\u5bf9\u8c61\u79f0\u4e3a \u201cvery plain\u201d \u6216 \u201cpure dictionary\u201d \u5bf9\u8c61\uff0c\u56e0\u4e3a\u5b83\u4eec\u751a\u81f3\u6bd4\u901a\u5e38\u7684\u666e\u901a\u5bf9\u8c61\uff08plain object\uff09<code>{...}<\/code>\u00a0\u8fd8\u8981\u7b80\u5355\u3002<br \/>\n\u7f3a\u70b9\u662f\u8fd9\u6837\u7684\u5bf9\u8c61\u6ca1\u6709\u4efb\u4f55\u5185\u5efa\u7684\u5bf9\u8c61\u7684\u65b9\u6cd5\uff0c\u4f8b\u5982\u00a0<code>toString<\/code><\/p>\n<pre><code class=\"language-js\">let obj = Object.create(null);\n\nalert(obj); \/\/ Error (no toString)\n<\/code><\/pre>\n<p>\u2026\u2026\u4f46\u662f\u5b83\u4eec\u901a\u5e38\u5bf9\u5173\u8054\u6570\u7ec4\u800c\u8a00\u8fd8\u662f\u5f88\u53cb\u597d\u3002<br \/>\n\u8bf7\u6ce8\u610f\uff0c\u5927\u591a\u6570\u4e0e\u5bf9\u8c61\u76f8\u5173\u7684\u65b9\u6cd5\u90fd\u662f\u00a0<code>Object.something(...)<\/code>\uff0c\u4f8b\u5982\u00a0<code>Object.keys(obj)<\/code>\u00a0\u2014\u2014 \u5b83\u4eec\u4e0d\u5728 prototype \u4e2d\uff0c\u56e0\u6b64\u5728 \u201cvery plain\u201d \u5bf9\u8c61\u4e2d\u5b83\u4eec\u8fd8\u662f\u53ef\u4ee5\u7ee7\u7eed\u4f7f\u7528\uff1a<\/p>\n<pre><code class=\"language-js\">let chineseDictionary = Object.create(null);\nchineseDictionary.hello = &quot;\u4f60\u597d&quot;;\nchineseDictionary.bye = &quot;\u518d\u89c1&quot;;\n\nalert(Object.keys(chineseDictionary)); \/\/ hello,bye\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>\u539f\u578b\u7ee7\u627f \u5728\u7f16\u7a0b\u4e2d\uff0c\u6211\u4eec\u7ecf\u5e38\u4f1a\u60f3\u83b7\u53d6\u5e76\u6269\u5c55\u4e00\u4e9b\u4e1c\u897f\u3002 \u4f8b\u5982\uff0c\u6211\u4eec\u6709\u4e00\u4e2a\u00a0user\u00a0\u5bf9\u8c61\u53ca\u5176\u5c5e\u6027\u548c\u65b9\u6cd5\uff0c\u5e76\u5e0c\u671b\u5c06 [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[19],"tags":[],"class_list":["post-635","post","type-post","status-publish","format-standard","hentry","category-front-end"],"_links":{"self":[{"href":"https:\/\/levin.ink\/index.php?rest_route=\/wp\/v2\/posts\/635","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/levin.ink\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/levin.ink\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/levin.ink\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/levin.ink\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=635"}],"version-history":[{"count":2,"href":"https:\/\/levin.ink\/index.php?rest_route=\/wp\/v2\/posts\/635\/revisions"}],"predecessor-version":[{"id":638,"href":"https:\/\/levin.ink\/index.php?rest_route=\/wp\/v2\/posts\/635\/revisions\/638"}],"wp:attachment":[{"href":"https:\/\/levin.ink\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=635"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/levin.ink\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=635"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/levin.ink\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=635"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}