{"id":1450,"date":"2022-07-26T19:07:25","date_gmt":"2022-07-26T11:07:25","guid":{"rendered":"https:\/\/zhuxinyong.com\/?p=1450"},"modified":"2022-08-07T18:00:16","modified_gmt":"2022-08-07T10:00:16","slug":"javascript-zhong-shen-me-shi-hou-shi-yong-map-geng","status":"publish","type":"post","link":"https:\/\/zhuxinyong.com\/?p=1450","title":{"rendered":"JavaScript \u4e2d\u4ec0\u4e48\u65f6\u5019\u4f7f\u7528 Map \u66f4\u5408\u9002"},"content":{"rendered":"<p><img decoding=\"async\" src=\"https:\/\/zhuxinyong.com\/wp-content\/uploads\/2022\/08\/\u8fd9\u7bc7\u6587\u7ae0\u771f\u7684\u5f88\u4e0d\u9519\u5f88\u597d\u516c\u4f17\u53f7\u9996\u56fe__2022-07-2909_07_42.jpeg\" alt=\"\u8fd9\u7bc7\u6587\u7ae0\u771f\u7684\u5f88\u4e0d\u9519\u5f88\u597d\u516c\u4f17\u53f7\u9996\u56fe__2022-07-29+09_07_42\" \/><\/p>\n<p><a href=\"https:\/\/www.zhenghao.io\/posts\/object-vs-map\" target=\"_blank\" rel=\"noopener\">https:\/\/www.zhenghao.io\/posts\/object-vs-map<\/a><\/p>\n<p>\u5728 JavaScript \u4e2d\uff0c\u5bf9\u8c61\u4f7f\u7528\u8d77\u6765\u5f88\u987a\u624b\uff0c\u5b83\u4f7f\u6211\u4eec\u53ef\u4ee5\u5f88\u65b9\u4fbf\u628a\u591a\u4e2a\u6570\u636e\u96c6\u5408\u5728\u4e00\u8d77\u3002\u5728 ES6 \u4e4b\u540e\u65b0\u589e\u4e86\u4e00\u4e2a\u6570\u636e\u7ed3\u6784\uff1a<code>Map<\/code>\u3002\u5b83\u770b\u8d77\u6765\u50cf\u4e00\u4e2a\u5e26\u6709\u4e00\u4e9b\u7b28\u62d9\u65b9\u6cd5\u66f4\u6709\u80fd\u529b\u7684 <code>Object<\/code>\u3002\u53ef\u662f\uff0c\u5f53\u5f00\u53d1\u8005\u9700\u8981 <code>hash map<\/code> \u65f6\u8fd8\u662f\u66f4\u4e60\u60ef\u4f7f\u7528\u5bf9\u8c61\uff0c\u76f4\u5230\u4ed6\u4eec\u610f\u8bc6\u4e00\u4e9b\u573a\u666f\u4e0b key \u4e0d\u80fd\u662f\u5b57\u7b26\u4e32\u624d\u4f1a\u60f3\u5230\u4f7f\u7528 <code>Map<\/code>\u3002\u56e0\u6b64\uff0c\u5728\u73b0\u5728\u7684 JavaScript \u793e\u533a\u4e2d <code>Map<\/code> \u5e76\u6ca1\u6709\u88ab\u5145\u5206\u5229\u7528\u3002<\/p>\n<p>\u5728\u8fd9\u7bc7\u6587\u7ae0\u4e2d\uff0c\u6211\u5c06\u4f1a\u9010\u4e00\u5206\u89e3\u66f4\u5e94\u8be5\u8003\u8651\u4f7f\u7528 <code>Map<\/code> \u7684\u539f\u56e0\u4ee5\u53ca\u5b83\u7684\u6027\u80fd\u4f18\u52bf\u3002<\/p>\n<blockquote>\n<p>\u5728 JavaScript \u4e2d\uff0c\u5bf9\u8c61\u662f\u4e00\u4e2a\u975e\u5e38\u5e7f\u6cdb\u7684\u672f\u8bed\u3002\u51e0\u4e4e\u4efb\u4f55\u4e1c\u897f\u90fd\u53ef\u4ee5\u4f5c\u4e3a\u5bf9\u8c61\uff0c\u9664\u4e86\u4e24\u79cd\u7c7b\u578b\uff1a<code>null<\/code> \u548c <code>undefined<\/code>\u3002\u5728\u8fd9\u7bc7\u6587\u7ae0\u4e2d\uff0c\u5bf9\u8c61\u4ec5\u4ec5\u4ee3\u8868<strong>plain object<\/strong>\uff0c\u901a\u8fc7\u5de6\u53f3\u62ec\u53f7\u5b9a\u4e49\u7684\u3002<\/p>\n<\/blockquote>\n<p>TL;DR:<\/p>\n<ul>\n<li>\u5f53\u4f60\u521b\u5efa\u7684\u5bf9\u8c61\u6709\u56fa\u5b9a\u548c\u6709\u7ebf\u6570\u91cf\u7684\u5c5e\u6027\u6216\u5b57\u6bb5\u65f6\u5219\u4f7f\u7528 <code>Object<\/code>\uff0c\u4f8b\u5982\u914d\u7f6e\u5bf9\u8c61\uff0c\u6216\u4efb\u4f55\u901a\u5e38\u53ea\u4f7f\u7528\u4e00\u6b21\u7684\u5bf9\u8c61\u3002<\/li>\n<li>\u5f53\u4f60\u7684\u5b57\u5178\u6216\u54c8\u5e0c\u6620\u5c04\u6761\u6570\u591a\u53d8\u4e14\u66f4\u65b0\u9891\u7e41\uff0c\u6216\u521b\u5efa\u65f6\u5173\u952e\u5b57\u4e0d\u786e\u5b9a\uff0c\u5219\u4f7f\u7528 <code>Map<\/code>\uff0c\u4f8b\u5982 <code>event emitter<\/code>\u3002<\/li>\n<li>\u66f4\u5177\u6211\u7684\u6d4b\u91cf\u6807\u51c6\uff0c\u9664\u4e86 key \u4e3a\u5c0f\u6574\u6570\u5b57\u7b26\u4e32\u65f6\uff0c\u5176\u4ed6\u60c5\u51b5\u5728\u63d2\u5165\u3001\u5220\u9664\u548c\u8fed\u4ee3\u65f6\uff0c \u540c\u7b49\u5927\u5c0f\u7684<code>Map<\/code> \u786e\u5b9e\u6bd4 <code>Object<\/code> \u66f4\u9ad8\u6548\u800c\u4e14\u6d88\u8017\u66f4\u5c0f\u7684\u5185\u5b58\u3002<\/li>\n<\/ul>\n<h2><a id=\"%E4%B8%BA%E4%BD%95object%E4%B8%8D%E8%B6%B3%E4%BB%A5%E8%AF%95%E7%94%A8-hash-map%E7%9A%84%E7%94%A8%E4%BE%8B\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u4e3a\u4f55 <code>Object<\/code> \u4e0d\u8db3\u4ee5\u8bd5\u7528 hash map \u7684\u7528\u4f8b<\/h2>\n<p>\u5f53\u5bf9\u8c61\u4f5c\u4e3a hash map \u65f6\uff0c\u6700\u660e\u663e\u7684\u7f3a\u70b9\u662f\u5b83\u53ea\u5141\u8bb8 key \u4e3a string \u548c symbol \u7c7b\u578b\uff0c\u5176\u5b83\u7c7b\u578b\u5219\u4f1a\u901a\u8fc7 <code>toString<\/code> \u9690\u5f0f\u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\u3002<\/p>\n<pre><code class=\"language-plain_text\">const foo = []\nconst bar = {}\nconst obj = {[foo]: 'foo', [bar]: 'bar'}\n\nconsole.log(obj) \/\/ {&quot;&quot;: 'foo', [object Object]: 'bar'}\n<\/code><\/pre>\n<p>\u66f4\u91cd\u8981\u7684\u662f\uff0c\u628a\u5bf9\u8c61\u4f5c\u4e3a hash map \u4f7f\u7528\u4f1a\u5f15\u8d77\u56f0\u60d1\u548c\u5b89\u5168\u9690\u60a3\u3002<\/p>\n<h2><a id=\"%E4%B8%8D%E9%9C%80%E8%A6%81%E7%9A%84%E7%BB%A7%E6%89%BF\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u4e0d\u9700\u8981\u7684\u7ee7\u627f<\/h2>\n<p>\u5728 ES6 \u4e4b\u524d\uff0c\u83b7\u53d6 hash map \u7684\u552f\u4e00\u65b9\u5f0f\u662f\u901a\u8fc7\u521b\u5efa\u4e00\u4e2a\u7a7a\u5bf9\u8c61\u3002<\/p>\n<pre><code class=\"language-plain_text\">const hashMap = {}\n<\/code><\/pre>\n<p>\u53ef\u662f\uff0c\u4e0a\u9762\u8bed\u53e5\u521b\u5efa\u7684\u5bf9\u8c61\u5e76\u4e0d\u662f\u4e00\u4e2a\u7a7a\u7684\u3002\u5373\u4f7f <code>hashMap<\/code> \u662f\u901a\u8fc7\u4e00\u4e2a\u7a7a\u7684\u5bf9\u8c61\u5b57\u9762\u91cf\u521b\u5efa\u7684\uff0c\u4f46\u5b83\u662f\u81ea\u52a8\u7ee7\u627f\u4e86 <code>Object.prototype<\/code> \u4e0a\u7684\u4e00\u4e9b\u65b9\u6cd5\u3002\u8fd9\u5c31\u662f\u4e3a\u4f55\u6211\u4eec\u53ef\u4ee5\u5728 <code>hashMap<\/code> \u4e0a\u8c03\u7528\u50cf <code>hasOwnProperty<\/code>\u3001<code>toString<\/code>\u3001<code>constructor<\/code> \u7b49\u65b9\u6cd5\uff0c\u5373\u4f7f\u6211\u4eec\u6ca1\u6709\u5728\u5b83\u4e0a\u9762\u663e\u793a\u7684\u5b9a\u4e49\u8fd9\u4e9b\u65b9\u6cd5\u3002<\/p>\n<p>\u56e0\u4e3a\u539f\u578b\u7ee7\u627f\uff0c\u73b0\u5728\u6211\u4eec\u7684\u5bf9\u8c61\u4e0a\u6709\u4e24\u79cd\u5c5e\u6027\u6df7\u5408\u5728\u4e00\u8d77\uff1a1. \u5bf9\u8c61\u4e0a\u76f4\u63a5\u5b9a\u4e49\u7684\uff08\u81ea\u8eab\u7684\uff09\uff1b2.\u539f\u578b\u94fe\u4e0a\u7684\uff08\u7ee7\u627f\u7684\u5c5e\u6027\uff09\u3002\u7ed3\u679c\u5c31\u662f\uff0c\u6211\u4eec\u9700\u8981\u53e6\u5916\u4e00\u4e2a\u68c0\u6d4b\u65b9\u6cd5\uff08\u4f8b\u5982\uff1ahasOwnProperty\uff09\u6765\u4fdd\u8bc1\u5c5e\u6027\u786e\u5b9e\u662f\u7528\u6237\u6dfb\u52a0\u7684\u800c\u4e0d\u662f\u4ece\u539f\u578b\u7ee7\u627f\u6765\u7684\u3002<\/p>\n<p>\u6700\u91cd\u8981\u7684\u662f\uff0c\u7531\u4e8e JavaScript \u4e2d\u5c5e\u6027\u7684\u67e5\u627e\u539f\u7406\uff0c\u8fd0\u884c\u65f6\u4efb\u4f55\u5bf9 <code>Object.prototype<\/code> \u7684\u53d8\u52a8\u90fd\u4f1a\u5f71\u54cd\u6240\u6709\u7684\u5bf9\u8c61\u3002\u8fd9\u5c31\u4e3a\u539f\u578b\u6c61\u67d3\u653b\u51fb\u5f00\u4e86\u4e00\u6247\u95e8\uff0c\u5bf9\u4e8e\u5927\u578b JavaScript \u5e94\u7528\u4f1a\u5e26\u6765\u4e25\u91cd\u7684\u5b89\u5168\u95ee\u9898\u3002<\/p>\n<p>\u5e78\u8fd0\u7684\u662f\uff0c\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7 <code>Object.create(null)<\/code> \u6765\u89e3\u51b3\u6b64\u95ee\u9898\uff0c\u5b83\u4f1a\u521b\u5efa\u4e00\u4e2a\u4ece <code>Object.prototype<\/code> \u6ca1\u6709\u7ee7\u627f\u4efb\u4f55\u5185\u5bb9\u7684\u5bf9\u8c61\u3002<\/p>\n<h2><a id=\"%E5%90%8D%E5%AD%97%E5%86%B2%E7%AA%81\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u540d\u5b57\u51b2\u7a81<\/h2>\n<p>\u5f53\u5bf9\u8c61\u4e0a\u81ea\u5df1\u7684\u5c5e\u6027\u540d\u548c\u539f\u578b\u4e0a\u51b2\u7a81\u65f6\uff0c\u5b83\u4f1a\u5f15\u53d1\u610f\u5916\u7684\u7ed3\u679c\u4ee5\u53ca\u4f7f\u4f60\u7a0b\u5e8f\u5d29\u6e83\u3002<\/p>\n<p>\u4f8b\u5982\uff0c\u6211\u4eec\u6709\u4e00\u4e2a\u63a5\u53d7\u5bf9\u8c61\u7684 <code>foo<\/code> \u65b9\u6cd5\uff1a<\/p>\n<pre><code class=\"language-plain_text\">function foo(obj) {\n\t\/\/...\n\tfor (const key in obj) {\n\t\tif (obj.hasOwnProperty(key)) {\n\t\t\t\n\t\t}\n\t}\n}\n<\/code><\/pre>\n<p><code>obj.hasOwnProperty(key)<\/code> \u6709\u4e00\u4e2a\u660e\u663e\u5371\u5bb3\uff0c\u6839\u636e JavaScript \u4e2d\u5c5e\u6027\u67e5\u627e\u673a\u5236\uff0c\u82e5 <code>obj<\/code> \u5bf9\u8c61\u81ea\u8eab\u4e0a\u5305\u542b <code>hasOwnProperty<\/code>\uff0c\u5219\u4f1a\u9690\u85cf\u539f\u578b\u94fe\u4e0a\u7684 <code>Object.prototype.hasOwnProperty<\/code>\u3002\u7ed3\u679c\u5c31\u662f\uff0c\u4ee3\u7801\u8fd0\u884c\u65f6\u6211\u4eec\u4e0d\u77e5\u9053\u4f7f\u7528\u4e86\u54ea\u91cc\u7684\u65b9\u6cd5\u3002<\/p>\n<p>\u4e00\u4e9b\u9632\u5fa1\u5f0f\u53d8\u6210\u53ef\u4ee5\u907f\u514d\u53d1\u751f\u7c7b\u4f3c\u7684\u4e8b\u60c5\uff0c\u4f8b\u5982\uff1a\u6211\u4eec\u53ef\u4ee5\u4ece <code>Object.prototype<\/code> \u501f\u7528\u771f\u6b63\u7684 <code>hasOwnProperty<\/code> \u65b9\u6cd5\u3002<\/p>\n<pre><code class=\"language-plain_text\">function foo(obj) {\n\t\/\/...\n\tfor (const key in obj) {\n\t\tif (Object.prototype.hasOwnProperty.call(obj, key)) {\n\t\t\t\/\/ ...\n\t\t}\n\t}\n}\n<\/code><\/pre>\n<p>\u4e00\u4e2a\u7b80\u77ed\u7684\u65b9\u6cd5\u53ef\u4ee5\u4f7f\u7528\u5bf9\u8c61\u5b57\u9762\u91cf\uff0c\u5c31\u50cf\u8fd9\u6837\uff1a<code>{}.hasOwnProperty.call(key)<\/code>\uff0c\u53ef\u662f\u8fd9\u6837\u4f9d\u65e7\u663e\u5f97\u5f88\u590d\u6742\u3002\u8fd9\u5c31\u662f\u4e3a\u4f55\u65b0\u589e\u4e86\u4e00\u4e2a\u9759\u6001\u65b9\u6cd5\uff1a<code>Object.hasOwn<\/code>\u3002<\/p>\n<h2><a id=\"%E4%B8%8D%E5%A4%9F%E5%8F%8B%E5%A5%BD%E7%9A%84%E6%96%B9%E6%B3%95\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u4e0d\u591f\u53cb\u597d\u7684\u65b9\u6cd5<\/h2>\n<p><code>Object<\/code> \u6ca1\u6709\u63d0\u4f9b\u8db3\u591f\u53cb\u597d\u7684\u65b9\u6cd5\u7528\u4f5c hash map\uff0c\u4e00\u4e9b\u4efb\u52a1\u5e76\u4e0d\u80fd\u51ed\u76f4\u89c9\u5b8c\u6210\u3002<\/p>\n<h3><a id=\"size\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>size<\/h3>\n<p><code>Object<\/code> \u5e76\u6ca1\u6709\u63d0\u4f9b\u8d81\u624b\u7684\u65b9\u6cd5\u6765\u83b7\u53d6\u5176\u5927\u5c0f\uff0c\u5c31\u662f\u5c5e\u6027\u7684\u4e2a\u6570\u3002\u4f46\u662f\uff0c\u83b7\u53d6\u5bf9\u8c61\u5927\u5c0f\u7684\u65b9\u6cd5\u6709\u4e00\u4e9b\u7ec6\u5fae\u7684\u5dee\u522b\uff1a<\/p>\n<ul>\n<li>\u82e5\u4f60\u5173\u5fc3\u7684\u662f\u5b57\u7b26\u4e32\u3001\u53ef\u679a\u4e3e\u7684\u5c5e\u6027\uff0c\u4f60\u53ef\u4ee5\u901a\u8fc7 <code>Object.keys()<\/code> \u628a\u5c5e\u6027\u7684 key \u8f6c\u6362\u4e3a\u6570\u7ec4\u5e76\u83b7\u53d6\u5176\u957f\u5ea6\u3002<\/li>\n<li>\u5982\u679c\u4f60\u66f4\u65b0\u4e0d\u53ef\u679a\u4e3e\u5b57\u7b26\u4e32\u7684 key \uff0c\u4f60\u53ef\u4ee5\u4f7f\u7528 <code>Object.getOwnPropertyNames<\/code> \u6765\u83b7\u53d6 key \u7684\u5217\u8868\uff0c\u7136\u540e\u5f97\u5230\u5176\u957f\u5ea6\u3002<\/li>\n<li>\u82e5\u4f60\u66f4\u5173\u5fc3 symbol \u7684 key\uff0c\u5219\u9700\u8981\u4f7f\u7528 <code>getOwnPropertySymbols<\/code> \u6765\u83b7\u53d6\u6240\u6709\u7684 symbol \u7684 key \u6216\u901a\u8fc7 <code>Reflect.ownKeys<\/code> \u6765\u540c\u65f6\u83b7\u5f97\u5b57\u7b26\u4e32\u548c symbol \u7684 key\uff0c\u800c\u4e0d\u7ba1\u5176\u662f\u5426\u53ef\u679a\u4e3e\u3002<\/li>\n<\/ul>\n<p>\u4e0a\u9762\u6240\u6709\u7684\u65b9\u6cd5\u90fd\u662f <code>O(n)<\/code> \u590d\u6742\u5ea6\uff0c\u56e0\u4e3a\u5b83\u4eec\u9996\u5148\u90fd\u9700\u8981\u6784\u5efa\u4e00\u4e2a\u6570\u7ec4\u7136\u540e\u83b7\u53d6\u5b83\u7684\u957f\u5ea6\u3002<\/p>\n<h3><a id=\"%E8%BF%AD%E4%BB%A3\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u8fed\u4ee3<\/h3>\n<p>\u5faa\u73af\u5bf9\u8c61\u4f1a\u9047\u5230\u7c7b\u4f3c\u7684\u590d\u6742\u95ee\u9898\u3002<\/p>\n<p>\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528\u53e4\u8001\u7684 <code>for ... in<\/code> \u5faa\u73af\uff0c\u4f46\u662f\u5b83\u4f1a\u628a\u7ee7\u627f\u7684\u53ef\u679a\u4e3e\u5c5e\u6027\u5c55\u793a\u51fa\u6765\u3002<\/p>\n<pre><code class=\"language-plain_text\">Object.prototype.foo = 'bar'\n\nconst obj = {id: 1} \n\nfor (const key in obj) {\n\tconsole.log(key) \/\/ 'id', 'foo'\n}\n<\/code><\/pre>\n<p>\u7531\u4e8e\u5bf9\u8c61\u9ed8\u8ba4\u4e0d\u662f\u53ef\u8fed\u4ee3\u7684\uff0c\u6240\u4ee5\u6211\u4eec\u4e0d\u53ef\u4ee5\u628a\u5bf9\u8c61\u548c <code>for ... of<\/code> \u4e00\u8d77\u4f7f\u7528\uff0c\u9664\u975e\u6211\u4eec\u663e\u5f0f\u7684\u5728\u5bf9\u8c61\u4e0a\u5b9a\u4e49\u4e86 <code>Symbol.iterator<\/code> \u65b9\u6cd5\u3002<\/p>\n<p>\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7 <code>Object.keys<\/code>\u3001<code>Object.values<\/code> \u548c <code>Object.entries<\/code> \u6765\u83b7\u53d6\u4e00\u4e2a\u53ef\u679a\u4e3e\u7684\u5217\u8868\uff0c\u7136\u540e\u5faa\u73af\u904d\u5386\u5b83\uff0c\u4f46\u8fd9\u4f1a\u589e\u52a0\u989d\u5916\u7684\u6b65\u9aa4\u548c\u5f00\u9500\u3002<\/p>\n<p>\u6700\u540e\uff0ckey \u7684\u987a\u5174\u4e5f\u662f\u81ed\u540d\u662d\u8457\u4e0d\u53d7\u5f85\u89c1\u7684\u3002\u5728\u591a\u6570\u6d4f\u89c8\u5668\u4e2d\uff0c\u6570\u5b57\u7c7b\u578b\u7684 key \u6709\u66f4\u9ad8\u7684\u4f18\u5148\u7ea7\uff0c\u4f1a\u6392\u5728\u5b57\u7b26\u4e32\u7c7b\u578b key \u4e4b\u524d\uff0c\u5373\u4f7f\u5b57\u7b26\u4e32\u7c7b\u578b\u7684 key \u5148\u4e8e\u6570\u5b57\u7c7b\u578b\u7684 key \u6dfb\u52a0\u3002<\/p>\n<pre><code class=\"language-plain_text\">const obj = {}\n\nobj.foo = 'first'\nobj[2] = 'second'\nobj[1] = 'last'\n\nconsole.log(obj) \/\/ {1: 'last', 2: 'second', foo: 'first'}\n<\/code><\/pre>\n<h3><a id=\"clear\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>clear<\/h3>\n<p>\u4ece\u5bf9\u8c61\u4e0a\u5220\u9664\u6240\u6709\u7684\u5c5e\u6027\u5e76\u4e0d\u662f\u4e00\u4ef6\u5bb9\u6613\u7684\u4e8b\uff0c\u4f60\u5fc5\u987b\u901a\u8fc7 <code>delete<\/code> \u64cd\u4f5c\u7b26\u4e00\u4e2a\u4e2a\u7684\u5220\u9664\uff0c\u8fd9\u5f88\u65e9\u5c31\u77e5\u9053\u662f\u4e00\u4e2a\u5f88\u6162\u7684\u64cd\u4f5c\u3002\u4f46\u662f\uff0c\u6211\u7684\u57fa\u51c6\u6d4b\u8bd5\u8868\u660e\u5b83\u7684\u6027\u80fd\u5b9e\u9645\u4e0a\u5e76\u4e0d\u6bd4 Map.prototype.delete \u6162\u4e00\u4e2a\u6570\u91cf\u7ea7\uff0c\u7a0d\u540e\u4f1a\u8be6\u7ec6\u8bf4\u660e\u3002<\/p>\n<h3><a id=\"%E6%A3%80%E6%B5%8B%E5%B1%9E%E6%80%A7%E6%98%AF%E5%90%A6%E5%AD%98%E5%9C%A8\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u68c0\u6d4b\u5c5e\u6027\u662f\u5426\u5b58\u5728<\/h3>\n<p>\u6700\u540e\uff0c\u6211\u4eec\u4e0d\u80fd\u4f9d\u8d56\u901a\u8fc7 <code>.<\/code> \u548c <code>[]<\/code> \u7b26\u53f7\u6765\u68c0\u6d4b\u5c5e\u6027\u662f\u5426\u5b58\u5728\uff0c\u56e0\u4e3a\u5c5e\u6027\u503c\u53ef\u80fd\u88ab\u8bbe\u7f6e\u4e3a <code>undefined<\/code>\u3002\u53d6\u800c\u4ee3\u4e4b\u6211\u4eec\u5fc5\u987b\u4f7f\u7528 <code>Object.prototype.hasOwnProperty<\/code> \u6216 <code>Object.hasOwn<\/code> \u6765\u68c0\u6d4b\uff1a<\/p>\n<pre><code class=\"language-plain_text\">const obj = {a: undefined}\n\nObject.hasOwn(obj, 'a') \/\/ true\n<\/code><\/pre>\n<h2><a id=\"map%E7%94%A8%E4%BD%9C-hash-map\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>Map \u7528\u4f5c Hash Map<\/h2>\n<p>ES6 \u7ed9\u6211\u4eec\u5e26\u6765\u4e86 <code>Map<\/code>\uff0c\u5b83\u66f4\u9002\u5408\u5f53\u505a hash map \u7684\u7528\u4f8b\u3002<\/p>\n<p>\u9996\u5148\uff0c\u5b83\u5e76\u4e0d\u50cf <code>Object<\/code> \u90a3\u6837\u53ea\u5141\u8bb8 key \u4e3a string \u548c symobol\uff0c<code>Map<\/code> \u7684 key \u652f\u6301\u4efb\u4f55\u6570\u636e\u7c7b\u578b\u3002<\/p>\n<blockquote>\n<p>\u53ef\u662f\u5982\u679c\u4f60\u4f7f\u7528 <code>Map<\/code> \u4e3a\u5bf9\u8c61\u5b58\u50a8\u5143\u6570\u636e\uff0c\u5e94\u8be5\u4f7f\u7528 <code>WeakMap<\/code> \u53d6\u800c\u4ee3\u4e4b\u4ee5\u6b64\u907f\u514d\u5185\u5b58\u6cc4\u6f0f\u3002<\/p>\n<\/blockquote>\n<p>\u66f4\u91cd\u8981\u7684\u662f\uff0c<code>Map<\/code> \u4e3a\u7528\u6237\u81ea\u5b9a\u4e49\u548c\u5185\u7f6e\u5bf9\u8c61\u5c5e\u6027\u63d0\u4f9b\u4e86\u6e05\u6670\u7684\u754c\u9650\uff0c\u4f7f\u7528\u4e00\u4e2a\u989d\u5916\u7684\u65b9\u6cd5 <code>Map.prototype.get<\/code> \u83b7\u53d6\u6761\u76ee\u3002<\/p>\n<p><code>Map<\/code> \u540c\u6837\u4e5f\u63d0\u4f9b\u4e86\u66f4\u4eba\u6027\u5316\u7684\u65b9\u6cd5\uff0c<code>Map<\/code> \u9ed8\u8ba4\u5c31\u53ef\u8fed\u4ee3\uff0c\u610f\u5473\u7740\u4f60\u53ef\u4ee5\u8f7b\u677e\u7684\u4e0e <code>for...of<\/code> \u4e00\u8d77\u4f7f\u7528\uff0c\u540c\u6837\u4f7f\u7528\u5d4c\u5957\u7684\u89e3\u6784\u83b7\u53d6\u7b2c\u4e00\u4e2a\u6761\u76ee\u3002<\/p>\n<pre><code class=\"language-plain_text\">const [[firstKey, firstValue]] = map\n<\/code><\/pre>\n<p>\u4e0e <code>Object<\/code> \u5bf9\u6bd4\uff0c<code>Map<\/code> \u4e3a\u5404\u79cd\u5e38\u89c1\u4efb\u52a1\u63d0\u4f9b\u4e86\u5177\u4f53\u7684\u65b9\u6cd5\uff1a<\/p>\n<ul>\n<li><code>Map.prototype.has<\/code> \u68c0\u67e5\u4e00\u4e2a\u7ed9\u5b9a\u6761\u76ee\u7684\u5b58\u5728\uff0c\u4e0e\u5bf9\u8c61\u4e0a\u7684 <code>Object.prototype.hasOwnProperty<\/code> \/ <code>Object.hasOwn<\/code> \u5bf9\u6bd4\u8fd8\u662f\u65b9\u4fbf\u8bb8\u591a\u3002<\/li>\n<li><code>Map.prototype.get<\/code> \u8fd4\u56de\u4e0e\u63d0\u4f9b\u7684 key \u76f8\u5173\u7684\u503c\u3002\u53ef\u80fd\u4f1a\u6709\u4eba\u89c9\u5f97\u6bd4\u5bf9\u8c61\u4e0a\u7684 <code>.<\/code> \u548c <code>[]<\/code> \u7a0d\u663e\u7b28\u91cd\u3002\u7136\u540e\u5b83\u4e3a\u7528\u6237\u81ea\u5b9a\u4e49\u7684\u6570\u636e\u548c\u5185\u7f6e\u7684\u65b9\u6cd5\u63d0\u4f9b\u4e86\u6e05\u6670\u7684\u754c\u9650\u3002<\/li>\n<li><code>Map.prototype.clear<\/code> \u53ef\u4ee5\u6e05\u9664 <code>Map<\/code> \u4e0a\u7684\u6240\u6709\u6761\u76ee\u4e14\u6bd4 <code>delete<\/code> \u64cd\u4f5c\u66f4\u5feb\u3002<\/li>\n<\/ul>\n<h2><a id=\"%E6%80%A7%E8%83%BD\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u6027\u80fd<\/h2>\n<p>\u5728 JavaScript \u793e\u533a\u4e2d\u4f3c\u4e4e\u6709\u4e00\u79cd\u5171\u540c\u7684\u8ba4\u77e5\uff1a<code>Map<\/code> \u6bd4 <code>Object<\/code> \u5feb\uff0c\u5728\u591a\u6570\u60c5\u51b5\u4e0b\uff0c\u6709\u4e9b\u4eba\u5728\u4ece <code>Object<\/code> \u5207\u6362\u5230 <code>Map<\/code> \u65f6\u770b\u5230\u4e86\u6027\u80fd\u7684\u63d0\u5347\u3002<\/p>\n<p>\u4ece\u6211\u5728\u78e8\u4eba\u7684 LeetCode \u4e2d\u5237\u9898\u7684\u7ecf\u9a8c\u4e2d\u4f3c\u4e4e\u66f4\u52a0\u786e\u8ba4\u4e86\u8fd9\u4e2a\u89c2\u70b9\uff1aLeetCode \u4f7f\u7528\u4e86\u5927\u91cf\u7684\u6570\u636e\u6765\u5bf9\u4f60\u7684\u89e3\u51b3\u65b9\u6848\u505a\u6d4b\u8bd5\u7528\u4f8b\uff0c\u82e5\u4f60\u7684\u7b54\u6848\u82b1\u8d39\u4e86\u592a\u957f\u65f6\u95f4\u5219\u4f1a\u8d85\u65f6\u3002\u50cf\u8fd9\u79cd\u95ee\u9898\u4e00\u822c\u5728\u4f60\u4f7f\u7528 <code>Object<\/code> \u65f6\u51fa\u73b0\u51e0\u6b21\uff0c\u800c <code>Map<\/code> \u5219\u6ca1\u6709\u3002<\/p>\n<p>\u53ef\u662f\uff0c\u6211\u76f8\u4fe1\u53ea\u7b80\u5355\u7684\u8bf4 <code>Map<\/code> \u6bd4 <code>Object<\/code> \u5feb\u5f88\u7b3c\u7edf\uff0c\u80af\u5b9a\u6709\u4e00\u4e9b\u7ec6\u5fae\u7684\u5dee\u522b\u9700\u8981\u6211\u53bb\u53d1\u73b0\u3002\u56e0\u6b64\uff0c\u6211\u521b\u5efa\u4e86\u4e00\u4e2a\u5c0f\u5e94\u7528\u6765\u8fd0\u884c\u4e00\u4e9b\u57fa\u51c6\u6d4b\u8bd5\u3002<\/p>\n<h2><a id=\"%E5%9F%BA%E5%87%86%E6%B5%8B%E8%AF%95%E7%9A%84%E5%AE%9E%E7%8E%B0%E7%BB%86%E8%8A%82\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u57fa\u51c6\u6d4b\u8bd5\u7684\u5b9e\u73b0\u7ec6\u8282<\/h2>\n<p>\u8fd9\u4e2a\u5e94\u7528\u6709\u4e00\u4e2a\u8868\u683c\u7528\u6765\u5c55\u793a\u5206\u522b\u5bf9 <code>Object<\/code> \u548c <code>Map<\/code> \u4f5c\u7528\u63d2\u5165\u3001\u8fed\u4ee3\u548c\u5220\u9664\u7684\u901f\u5ea6\u3002<\/p>\n<p>\u63d2\u5165\u548c\u8fed\u4ee3\u7684\u6027\u80fd\u662f\u4ee5\u6bcf\u79d2\u6765\u6d4b\u91cf\u7684\uff0c\u6211\u5199\u4e86\u4e00\u4e2a\u5de5\u5177\u65b9\u6cd5 <code>measureFor<\/code> \u7528\u6765\u91cd\u590d\u6267\u884c\u76ee\u6807\u51fd\u6570\uff0c\u76f4\u5230\u8bbe\u5b9a\u7684\u6700\u5c0f\u9608\u503c\uff08\u5c31\u662f\u4f20\u5165\u7684 <code>duration<\/code> \u503c\uff09\u3002\u5b83\u8fd4\u56de\u7684\u662f\u6bcf\u79d2\u51fd\u6570\u6267\u884c\u7684\u5e73\u5747\u6b21\u6570\u3002<\/p>\n<pre><code class=\"language-plain_text\">function measureFor(f, duration) {\n  let iterations = 0;\n  const now = performance.now();\n  let elapsed = 0;\n  while (elapsed &lt; duration) {\n    f();\n    elapsed = performance.now() - now;\n    iterations++;\n  }\n\n  return ((iterations \/ elapsed) * 1000).toFixed(4);\n}\n<\/code><\/pre>\n<p>\u5bf9\u4e8e\u5220\u9664\uff0c\u6211\u6253\u7b97\u7b80\u5355\u7684\u5bf9\u6bd4\u4e00\u4e0b\u4ece\u957f\u5ea6\u76f8\u540c\u7684 <code>Object<\/code> \u3001 <code>Map<\/code> \u5206\u522b\u4f7f\u7528 <code>delete<\/code> \u548c <code>Map.protoype.delete<\/code> \u79fb\u9664\u6240\u6709\u5c5e\u6027\u6240\u82b1\u8d39\u65f6\u95f4\u7684\u5bf9\u6bd4\u3002\u6211\u77e5\u9053\u6709 <code>Map.protype.clear<\/code> \u4f46\u636e\u6211\u6240\u77e5\u5b83\u975e\u5e38\u7684\u5feb\uff0c\u8fd9\u6709\u6096\u4e8e\u8bbe\u7f6e\u57fa\u7840\u6d4b\u8bd5\u7684\u76ee\u7684\u3002<\/p>\n<p>\u5728\u8fd9\u4e09\u79cd\u64cd\u4f5c\u4e2d\uff0c\u56e0\u4e3a\u6bcf\u5929\u7684\u5de5\u4f5c\u4e2d\u7ecf\u5e38\u4f7f\u7528\u5230\u63d2\u5165\u64cd\u4f5c\uff0c\u6240\u4ee5\u6211\u66f4\u5173\u5fc3\u5b83\u3002\u5bf9\u4e8e\u8fed\u4ee3\u7684\u6027\u80fd\uff0c\u56e0\u4e3a\u6709\u5f88\u591a\u65b9\u6cd5\u7528\u4e8e\u5bf9\u8c61\u7684\u8fed\u4ee3\uff0c\u6240\u4ee5\u5f88\u96be\u5305\u542b\u6240\u6709\u7684\u57fa\u51c6\u6d4b\u8bd5\u3002\u6211\u5728\u8fd9\u91cc\u53ea\u6d4b\u8bd5\u4e86 <code>for ... in<\/code> \u5faa\u73af\u3002<\/p>\n<p>\u6211\u8fd9\u91cc\u4f7f\u7528\u4e86\u4e09\u79cd\u7c7b\u578b\u7684 key:<\/p>\n<ul>\n<li>\u5b57\u7b26\u4e32\uff0c\u4f8b\u5982\uff1a<code>'yekwl7caqejth7aawelo4'<\/code>\u3002<\/li>\n<li>\u6574\u6570\u5b57\u7b26\u4e32\uff0c\u4f8b\u5982\uff1a<code>123<\/code>\u3002<\/li>\n<li>\u901a\u8fc7 <code>Math.random().toString()<\/code> \u751f\u4ea7\u7684\u6570\u5b57\u5b57\u7b26\u4e32\uff0c\u4f8b\u5982\uff1a<code>'0.6514674912156457'<\/code><\/li>\n<\/ul>\n<p>\u6240\u6709\u7684 key \u90fd\u662f\u968f\u673a\u751f\u6210\u7684\uff0c\u6240\u4ee5\u4e0d\u4f1a\u89e6\u53d1 V8 \u5185\u90e8\u5b9e\u73b0\u7684\u7f13\u5b58\u673a\u5236\u3002\u5728\u628a\u5c5e\u6027\u6dfb\u52a0\u5230\u5bf9\u8c61\u4e0a\u4e4b\u524d\uff0c\u6211\u8fd8\u5728\u663e\u6027\u7684\u628a\u6574\u6570\u548c\u6570\u503c\u7c7b\u578b\u7684 key \u901a\u8fc7 <code>toString<\/code> \u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\u4ee5\u6b64\u907f\u514d\u9690\u5f0f\u5f00\u9500\u3002<\/p>\n<p>\u6700\u540e\uff0c\u5728\u57fa\u51c6\u6d4b\u8bd5\u5f00\u59cb\u4e4b\u524d\uff0c\u8fd8\u6709\u4e00\u4e2a 100ms \u7684\u70ed\u8eab\u9636\u6bb5\uff0c\u5c31\u662f\u91cd\u590d\u521b\u5efa\u65b0\u7684 object \u548c map \u5e76\u7acb\u5373\u4e22\u5f03\u6389\u6240\u8017\u8d39\u7684\u65f6\u95f4\u3002<\/p>\n<p>\u6211\u5df2\u7ecf\u628a\u4ee3\u7801\u653e\u5230\u4e86 <a href=\"https:\/\/codesandbox.io\/s\/still-glitter-yuu1dm\" target=\"_blank\" rel=\"noopener\">CodeSandbox<\/a> \u5982\u679c\u4f60\u60f3\u8bd5\u73a9\u4e00\u4e0b\u3002<\/p>\n<p>\u6211\u4ece 100 \u4e2a\u5c5e\u6027\/\u6761\u76ee\u5927\u5c0f\u7684 Object \u548c Map \u5f00\u59cb\uff0c\u4e00\u76f4\u52305000000\uff0c\u6bcf\u79cd\u7c7b\u578b\u7684\u64cd\u4f5c\u90fd\u6267\u884c\u4e86 10000ms \u6765\u5bf9\u6bd4\u5b83\u4eec\u4e4b\u95f4\u7684\u8868\u73b0\uff0c\u4e0b\u9762\u662f\u6211\u53d1\u73b0\u7684:<\/p>\n<blockquote>\n<p><strong>\u4e3a\u4f55\u628a\u6761\u76ee\u6570\u8fbe\u5230 5000000\u65f6\u624d\u505c\u6b62\uff1f<\/strong><br \/>\n\u8fd9\u662f JavaScript \u4e2d\u80fd\u5f97\u5230\u7684\u6700\u5927\u5bf9\u8c61\uff0c\u6839\u636e StackOverflow \u4e0a\u4e00\u540d\u6d3b\u8dc3\u7684 V8 \u5de5\u7a0b\u5e08 @jmrk \u6240\u8bf4\uff1a&quot;\u5982\u679c key \u4e3a\u5b57\u7b26\u4e32\uff0c\u5f53\u4e00\u4e2a\u666e\u901a\u7684\u5bf9\u8c61\u5143\u7d20\u8fbe\u5230 8.3M \u65f6\u4f1a\u5404\u79cd\u5bf9\u5b83\u7684\u64cd\u4f5c\u4f1a\u53d8\u5f97\u975e\u5e38\u6162\uff08\u8fd9\u662f\u6709\u6280\u672f\u539f\u56e0\u7684\uff1a\u67d0\u4e2a\u4f4d\u57df\u670923\u4f4d\u5bbd\uff0c\u5f53\u8d85\u8fc7\u65f6\u91c7\u53d6\u975e\u5e38\u7f13\u6162\u7684\u56de\u9000\u8def\u5f84\u3002\uff09&quot;<\/p>\n<\/blockquote>\n<h3><a id=\"%E5%AD%97%E7%AC%A6%E4%B8%B2key\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u5b57\u7b26\u4e32 key<\/h3>\n<p>\u901a\u5e38\u6765\u8bf4\uff0c\u5f53 key \u4e3a\u5b57\u7b26\u4e32\uff08\u975e\u6570\u503c\u578b\uff09\uff0c\u5728\u5404\u79cd\u64cd\u4f5c\u4e2d <code>Map<\/code> \u7684\u8868\u73b0\u80dc\u8fc7 <code>Object<\/code>\u3002<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/zhuxinyong.com\/wp-content\/uploads\/2022\/08\/16597083013942-scaled.jpg\" alt=\"\" \/><\/p>\n<p>\u4f46\u662f\u5f53\u6761\u76ee\u6570\u5e76\u6ca1\u6709\u7279\u522b\u5927\u7684\u65f6\u5019\uff08100000 \u4ee5\u4e0b\u7684\u65f6\u5019\uff09\uff0c\u5728\u63d2\u5165\u64cd\u4f5c\u7684\u901f\u5ea6\u4e0a <code>Map<\/code> \u57fa\u672c\u662f <code>Object<\/code> \u7684\u4e24\u500d\uff0c\u4f46\u5f53\u5927\u5c0f\u8d85\u8fc7 100000 \u65f6\uff0c\u6027\u80fd\u5dee\u8ddd\u4f1a\u5f00\u59cb\u7f29\u5c0f\u3002<\/p>\n<p>\u6211\u5236\u4f5c\u4e86\u4e00\u4e2a\u56fe\u8868\u6765\u8bf4\u660e\u6211\u7684\u53d1\u73b0\uff1a<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/zhuxinyong.com\/wp-content\/uploads\/2022\/08\/16597086258288-scaled.jpg\" alt=\"\" \/><\/p>\n<p>\u4e0a\u9762\u7684\u56fe\u8868\u6f14\u793a\u4e86\u63d2\u5165\u901f\u7387\u968f\u7740\u6761\u76ee\u6570\uff08x-axis\uff09\u7684\u589e\u52a0\u662f\u5982\u4f55\u4e0b\u964d\u7684\uff08y-axis\uff09\u3002\u53ef\u662f\uff0c\u56e0\u4e3a x-axis \u6269\u5c55\u7684\u8d8a\u6765\u8d8a\u5927\uff08\u4ece 100 \u5230 1000000\uff09\uff0c\u5f88\u96be\u533a\u5206\u51fa\u4e24\u6761\u7ebf\u4e4b\u95f4\u7684\u95f4\u9694\u5dee\u8ddd\u3002<\/p>\n<p>\u7136\u540e\u6211\u7528\u5bf9\u6570\u6bd4\u4f8b\u6765\u5904\u7406\u6570\u636e\uff0c\u505a\u51fa\u4e86\u4e0b\u9762\u7684\u56fe\u8868\uff1a<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/zhuxinyong.com\/wp-content\/uploads\/2022\/08\/16597089922361.jpg\" alt=\"\" \/><\/p>\n<p>\u4f60\u4f1a\u6e05\u695a\u7684\u5206\u4e0d\u51fa\u4e24\u6761\u7ebf\u6e10\u6e10\u5730\u91cd\u53e0\u3002<\/p>\n<p>\u6211\u53c8\u7528\u53e6\u4e00\u4e2a\u56fe\u8868\u6765\u5c55\u793a\u5f53\u63d2\u5165\u64cd\u7eb5\u65f6 <code>Map<\/code> \u6bd4 <code>Object<\/code> \u5feb\u591a\u5c11\u3002\u4f60\u53ef\u4ee5\u770b\u5230\u671f\u521d <code>Map<\/code> \u6bd4 <code>Object<\/code> \u5feb 2\u500d\uff0c\u968f\u7740\u65f6\u95f4\u7684\u63a8\u79fb\u6027\u80fd\u5dee\u8ddd\u5f00\u59cb\u7f29\u5c0f\u3002\u6700\u7ec8\uff0c\u5f53\u5927\u5c0f\u8fbe\u5230 5000000 \u65f6\uff0c<code>Map<\/code> \u53ea\u5feb\u4e86 30%\u3002<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/zhuxinyong.com\/wp-content\/uploads\/2022\/08\/16597096148872.jpg\" alt=\"\" \/><\/p>\n<p>\u6211\u4eec\u7684 object \u548c map \u7684\u6761\u76ee\u6c38\u8fdc\u4e0d\u53ef\u80fd\u591a\u4f59 1\u767e\u4e07\u3002\u6210\u767e\u4e0a\u5343\u7684\u6761\u76ee\uff0c<code>Map<\/code> \u81f3\u5c11\u6bd4 <code>Object<\/code> \u5feb 2 \u500d\u3002\u56e0\u6b64\uff0c\u6211\u4eec\u662f\u5426\u5e94\u8be5\u5f00\u59cb\u4f7f\u7528 <code>Map<\/code> \u6765\u91cd\u6784\u6211\u4eec\u7684\u4ee3\u7801\uff1f<\/p>\n<p>\u5f53\u7136\u4e0d\u662f\uff0c\u81f3\u5c11\u4e0d\u80fd\u671f\u671b\u6211\u4eec\u7684\u7a0b\u5e8f\u53d8\u5f97\u6bd4\u4e4b\u524d\u5feb 2\u500d\u3002\u8bb0\u4f4f\u6211\u4eec\u8fd8\u6ca1\u6709\u63a2\u7d22\u5176\u5b83\u7c7b\u578b\u7684 key\uff0c\u63a5\u4e0b\u6765\u8ba9\u6211\u4eec\u4e00\u8d77\u770b\u770b\u6574\u6570\u7c7b\u578b\u7684 key\u3002<\/p>\n<h2><a id=\"%E6%95%B4%E6%95%B0%E7%B1%BB%E5%9E%8B%E7%9A%84%E9%94%AE\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u6574\u6570\u7c7b\u578b\u7684\u952e<\/h2>\n<p>\u6211\u7279\u522b\u60f3\u8fd0\u884c\u5bf9\u8c61\u4e0a\u952e\u4e3a\u6574\u6570\u7c7b\u578b\u7684\u539f\u56e0\u662f V8 \u5185\u90e8\u4e3a\u6574\u6570\u7d22\u5f15\u7684\u5c5e\u6027\u505a\u4e86\u4f18\u5316\u4ee5\u53ca\u628a\u5b83\u4eec\u5b58\u50a8\u5728\u4e00\u4e2a\u5206\u5f00\u7684\u6570\u7ec4\u4e2d\uff0c\u7136\u540e\u53ef\u4ee5\u7ebf\u6027\u548c\u8fde\u7eed\u7684\u83b7\u53d6\u3002\u53ef\u662f\u6211\u6ca1\u6709\u627e\u5230\u4efb\u4f55\u8d44\u6599\u6765\u8bc1\u660e V8 \u5bf9 <code>Map<\/code> \u505a\u4e86\u540c\u6837\u7684\u4f18\u5316\u3002<\/p>\n<p>\u6211\u4eec\u5148\u5728 [0,1000] \u4e4b\u95f4\u5c1d\u8bd5\u6574\u6570\u7c7b\u578b\u7684 key\u3002<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/zhuxinyong.com\/wp-content\/uploads\/2022\/08\/16598047571367-scaled.jpg\" alt=\"\" \/><\/p>\n<p>\u5c31\u50cf\u6211\u9884\u671f\u7684\u4e00\u6837\uff0c\u8fd9\u6b21 <code>Object<\/code> \u6bd4 <code>Map<\/code> \u505a\u5f97\u597d\uff0c\u5728\u63d2\u5165\u65b9\u9762\u5feb 65%\u4ee5\u53ca\u5faa\u73af\u65b9\u9762\u5feb 16%\u3002<\/p>\n<p>\u8ba9\u6211\u4eec\u628a\u8303\u56f4\u8c03\u6574\u5230\u6700\u5927 1200\u3002<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/zhuxinyong.com\/wp-content\/uploads\/2022\/08\/16598049313907-scaled.jpg\" alt=\"\" \/><\/p>\n<p>\u73b0\u5728\u770b\u8d77\u6765 <code>Map<\/code> \u5728\u63d2\u5165\u65b9\u9762\u5feb\u4e00\u4e9b\u4ee5\u53ca\u5faa\u73af\u65b9\u4fbf\u5feb 5 \u500d\u3002<\/p>\n<p>\u73b0\u5728\u6211\u4eec\u4ec5\u4ec5\u589e\u52a0\u4e86\u952e\u7684\u8303\u56f4\uff0c\u800c\u4e0d\u662f <code>Object<\/code> \u548c <code>Map<\/code> \u7684\u5b9e\u9645\u5927\u5c0f\u3002\u8ba9\u6211\u4eec\u6765\u589e\u52a0\u5b83\u4eec\u7684\u5927\u5c0f\u770b\u770b\u5982\u4f55\u5f71\u54cd\u6027\u80fd\u3002<\/p>\n<p><img decoding=\"async\" src=\"https:\/\/zhuxinyong.com\/wp-content\/uploads\/2022\/08\/16598052081316-scaled.jpg\" alt=\"\" \/><\/p>\n<p>\u5f53\u5927\u5c0f\u4e3a 1000 \u65f6\uff0c\u63d2\u5165\u65b9\u9762 <code>Object<\/code> \u6bd4 <code>Map<\/code> \u5feb 70% \u4ee5\u53ca\u5faa\u73af\u65b9\u9762\u5feb 2 \u500d\u3002<\/p>\n<p>\u6211\u5c1d\u8bd5\u4e86\u5f88\u591a\u79cd <code>Object<\/code> \/ <code>Map<\/code> \u5927\u5c0f\u4e0e\u6574\u6570\u952e\u8303\u56f4\u7684\u7ec4\u5408\u4f46\u6ca1\u6709\u5f97\u5230\u4e00\u4e2a\u6e05\u6670\u7684\u6a21\u5f0f\u3002\u4f46\u6211\u770b\u5230\u7684\u4e00\u822c\u8d8b\u52bf\u662f\uff0c\u968f\u7740\u5927\u5c0f\u7684\u589e\u957f\uff0c\u4ee5\u4e00\u4e9b\u76f8\u5bf9\u8f83\u5c0f\u7684\u6574\u6570\u4e3a\u952e\uff0c\u5bf9\u8c61\u5728\u63d2\u5165\u65b9\u9762\u7684\u6027\u80fd\u6bd4 Map \u66f4\u5f3a\uff0c\u5728\u5220\u9664\u65b9\u9762\u603b\u662f\u5927\u81f4\u76f8\u540c\uff0c\u8fed\u4ee3\u901f\u5ea6\u8981\u6162 4 \u6216 5 \u500d\u3002\u5bf9\u8c61\u5728\u63d2\u5165\u65f6\u5f00\u59cb\u53d8\u6162\u7684\u6700\u5927\u6574\u6570\u952e\u7684\u9608\u503c\u4f1a\u968f\u7740\u5bf9\u8c61\u7684\u5927\u5c0f\u800c\u589e\u957f\u3002\u4f8b\u5982\uff0c\u5f53\u5bf9\u8c61\u53ea\u6709 100 \u4e2a\u6761\u76ee\u65f6\uff0c\u9608\u503c\u662f 1200 \uff1b\u5f53\u5b83\u6709 10000 \u4e2a\u6761\u76ee\u65f6\uff0c\u9608\u503c\u4f3c\u4e4e\u662f 24000 \u5de6\u53f3\u3002<\/p>\n<h2><a id=\"%E6%95%B0%E5%80%BC%E7%B1%BB%E5%9E%8B%E7%9A%84%E9%94%AE\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u6570\u503c\u7c7b\u578b\u7684\u952e<\/h2>\n<p>\u6700\u540e\uff0c\u6211\u4eec\u4e00\u8d77\u770b\u4e00\u770b\u6700\u540e\u4e00\u79cd\u7c7b\u578b\u7684\u952e&#8211;\u6570\u503c\u578b\u3002<\/p>\n<p>\u4ece\u6280\u672f\u4e0a\u6765\u8bf4\uff0c\u524d\u9762\u7684\u6574\u6570\u7c7b\u578b\u7684\u952e\u4e5f\u662f\u6570\u503c\u578b\uff0c\u4e0d\u8fc7\u8fd9\u91cc\u7684\u6570\u503c\u578b\u7279\u6307\u901a\u8fc7 <code>Math.random().toString()<\/code> \u751f\u6210\u7684\u6570\u503c\u5b57\u7b26\u4e32\u3002<\/p>\n<p>\u7ed3\u679c\u6709\u70b9\u7c7b\u4f3c\u5b57\u7b26\u4e32\u7c7b\u578b\u7684\u952e\uff1a<code>Map<\/code> \u5f00\u59cb\u65f6\u6bd4 <code>Object<\/code> \u5feb\u5f97\u591a\uff08\u63d2\u5165\u548c\u5220\u9664\u5feb2\u500d\uff0c\u8fed\u4ee3\u5feb4-5\u500d\uff09\uff0c\u4f46\u968f\u7740\u6211\u4eec\u89c4\u6a21\u7684\u589e\u52a0\uff0c\u8fd9\u4e2a\u5dee\u8ddd\u4e5f\u8d8a\u6765\u8d8a\u5c0f\u3002<\/p>\n<blockquote>\n<p>\u5d4c\u5957\u7684 Object \/ Map \u5462\uff1f<br \/>\n\u4f60\u53ef\u80fd\u5df2\u7ecf\u53d1\u73b0\u4e86\u6211\u53ea\u8bb2\u4e86\u6df1\u5ea6\u53ea\u6709\u4e00\u5c42\u7684 <code>Object<\/code> \u548c <code>Map<\/code>\u3002\u6211\u786e\u5b9e\u589e\u52a0\u4e86\u4e00\u4e9b\u5d4c\u5957\u6df1\u5ea6\u4f46\u662f\u6211\u53d1\u73b0\u53ea\u8981\u603b\u6761\u76ee\u6570\u76f8\u540c\u6027\u80fd\u7279\u6027\u5927\u4f53\u4e00\u81f4\uff0c\u4e0d\u7ba1\u5d4c\u5957\u4e86\u591a\u5c11\u5c42\u3002<\/p>\n<p>\u4f8b\u5982\uff0c\u6211\u4eec\u6709\u4e00\u4e2a\u5bbd\u5ea6\u4e3a 100 \u548c\u6df1\u5ea6\u4e3a 3 \u603b\u6570\u4e3a 100 \u4e07\u7684\u6761\u76ee\uff0c\u7ed3\u679c\u4e0e\u5bbd\u5ea6\u4e3a 1000000 \u6df1\u5ea6\u4e3a 1 \u7684\u6027\u80fd\u51e0\u4e4e\u76f8\u540c\u3002<\/p>\n<\/blockquote>\n<h2><a id=\"%E5%86%85%E5%AD%98%E4%BD%BF%E7%94%A8\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u5185\u5b58\u4f7f\u7528<\/h2>\n<p>\u57fa\u51c6\u6d4b\u8bd5\u7684\u53e6\u4e00\u4e2a\u91cd\u8981\u56e0\u7d20\u4e3a\u5185\u5b58\u5229\u7528\u3002<\/p>\n<p>\u7531\u4e8e\u6211\u65e0\u6cd5\u63a7\u5236\u6d4f\u89c8\u5668\u73af\u5883\u4e2d\u7684\u5783\u573e\u6536\u96c6\u5668\uff0c\u6211\u51b3\u5b9a\u5728Node\u4e2d\u8fd0\u884c\u57fa\u51c6\u6d4b\u8bd5\u3002<\/p>\n<p>\u6211\u521b\u5efa\u4e86\u4e00\u4e2a\u5c0f\u811a\u672c\u6765\u6d4b\u91cf\u5728\u6bcf\u4e2a\u6d4b\u8bd5\u4e2d\u901a\u8fc7\u624b\u52a8\u89e6\u53d1\u5b8c\u5168\u5783\u573e\u56de\u6536\u65f6\u5404\u81ea\u7684\u5185\u5b58\u4f7f\u7528\u60c5\u51b5\u3002\u4e0e <code>node --expose-gc<\/code> \u4e00\u8d77\u8fd0\u884c\u5c06\u4f1a\u5f97\u5230\u5982\u4e0b\u7ed3\u679c\uff1a<\/p>\n<pre><code class=\"language-plain_text\">{\n  object: {\n    'string-key': {\n      '10000': 3.390625,\n      '50000': 19.765625,\n      '100000': 16.265625,\n      '500000': 71.265625,\n      '1000000': 142.015625\n    },\n    'numeric-key': {\n      '10000': 1.65625,\n      '50000': 8.265625,\n      '100000': 16.765625,\n      '500000': 72.265625,\n      '1000000': 143.515625\n    },\n    'integer-key': {\n      '10000': 0.25,\n      '50000': 2.828125,\n      '100000': 4.90625,\n      '500000': 25.734375,\n      '1000000': 59.203125\n    }\n  },\n  map: {\n    'string-key': {\n      '10000': 1.703125,\n      '50000': 6.765625,\n      '100000': 14.015625,\n      '500000': 61.765625,\n      '1000000': 122.015625\n    },\n    'numeric-key': {\n      '10000': 0.703125,\n      '50000': 3.765625,\n      '100000': 7.265625,\n      '500000': 33.265625,\n      '1000000': 67.015625\n    },\n    'integer-key': {\n      '10000': 0.484375,\n      '50000': 1.890625,\n      '100000': 3.765625,\n      '500000': 22.515625,\n      '1000000': 43.515625\n    }\n  }\n}\n<\/code><\/pre>\n<p>\u5f88\u660e\u663e\uff0c<code>Map<\/code> \u6bd4 <code>Object<\/code> \u6d88\u8017\u7684\u5185\u5b58\u5c1120%\u523050%\u4e0d\u7b49\uff0c\u7ed3\u679c\u5e76\u4e0d\u610f\u5916\u56e0\u4e3a <code>Map<\/code> \u4e0d\u5b58\u50a8\u5c5e\u6027\u7684\u63cf\u8ff0\u7c7b\u4f3c <code>Object<\/code> \u4e0a\u7684 <code>writable<\/code> \u3001<code>enumerable<\/code> \u3001<code>configurable<\/code>\u3002<\/p>\n<h2><a id=\"%E6%80%BB%E7%BB%93\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u603b\u7ed3<\/h2>\n<p>\u90a3\u4e48\uff0c\u6211\u4eec\u4ece\u5176\u4e2d\u80fd\u5f97\u5230\u4ec0\u4e48\uff1f<\/p>\n<ul>\n<li><code>Map<\/code> \u6bd4 <code>Object<\/code> \u66f4\u5feb\uff0c\u9664\u975e\u4f60\u6709\u5c0f\u7684\u6574\u6570\u3001\u6570\u7ec4\u7d22\u5f15\u4e3a\u952e\uff0c\u800c\u4e14\u5b83\u66f4\u8282\u7701\u5185\u5b58\u3002<\/li>\n<li>\u82e5 Hash Map \u9700\u8981\u7ecf\u5e38\u66f4\u65b0\u4f60\u5e94\u8be5\u4f7f\u7528 <code>Map<\/code>\uff1b\u82e5\u4f60\u7684\u96c6\u5408\u4e3a\u56fa\u5b9a\u7684\u952e\u503c\uff08\u4f8b\u5982\uff1a\u8bb0\u5f55\uff09\u5219\u4f7f\u7528 <code>Object<\/code>\uff0c\u4f46\u662f\u8bf7\u6ce8\u610f\u539f\u578b\u7ee7\u627f\u5e26\u6765\u7684\u9677\u9631\u3002<\/li>\n<\/ul>\n<blockquote>\n<p>\u5982\u679c\u4f60\u77e5\u9053 V8 \u4f18\u5316 <code>Map<\/code> \u7684\u7ec6\u8282\uff0c\u6216\u8005\u53ea\u662f\u60f3\u6307\u51fa\u6211\u7684\u57fa\u51c6\u6d4b\u8bd5\u4e2d\u7684\u7f3a\u9677\uff0c\u8bf7\u4e0e\u6211\u8054\u7cfb\u3002\u6211\u5f88\u4e50\u610f\u6839\u636e\u4f60\u7684\u4fe1\u606f\u6765\u66f4\u65b0\u8fd9\u4e2a\u5e16\u5b50\u3002<\/p>\n<\/blockquote>\n<h2><a id=\"%E6%B5%8F%E8%A7%88%E5%99%A8%E5%85%BC%E5%AE%B9%E6%80%A7%E7%AC%94%E8%AE%B0\" class=\"anchor\" aria-hidden=\"true\"><span class=\"octicon octicon-link\"><\/span><\/a>\u6d4f\u89c8\u5668\u517c\u5bb9\u6027\u7b14\u8bb0<\/h2>\n<p><code>Map<\/code> \u662f ES6 \u5f15\u5165\u7684\u7279\u6027\uff0c\u76ee\u524d\u4e3a\u6b62\u6211\u4eec\u4e0d\u9700\u8981\u62c5\u5fc3\u5176\u517c\u5bb9\u6027\u9664\u975e\u4f60\u7684\u5ba2\u6237\u4f7f\u7528\u7684\u65e7\u6d4f\u89c8\u5668\u3002\u65e7\u6307\u6bd4 IE11 \u7248\u672c\u4f4e\uff0c\u5373\u4f7f IE11 \u652f\u6301 <code>Map<\/code> \u4f46\u5b83\u5df2\u7ecf <strong>\u6b7b<\/strong> \u4e86\u3002\u9ed8\u8ba4\u60c5\u51b5\u4e0b\uff0c\u6211\u4eec\u4e0d\u9700\u8981\u8d39\u5c3d\u5fc3\u601d\u7684\u6dfb\u52a0\u8f6c\u6362\u5668\u548c\u57ab\u7247\u6765\u652f\u6301 ES5 \uff0c\u56e0\u4e3a\u90a3\u6837\u4f1a\u589e\u52a0\u4f60\u7684\u6253\u5305\u4f53\u79ef\uff0c\u540c\u6837\u4e0e\u73b0\u4ee3\u6d4f\u89c8\u5668\u6bd4\u66f4\u6162\u3002\u6700\u91cd\u8981\u7684\u662f\uff0c\u90a3\u6837\u4f1a\u5bf9 99.999% \u4f7f\u7528\u73b0\u4ee3\u6d4f\u89c8\u5668\u7684\u7528\u6237\u5e26\u6765\u8d1f\u62c5\u3002<\/p>\n<p>\u53e6\u5916\uff0c\u6211\u4eec\u4e0d\u5fc5\u653e\u5f03\u5bf9\u4f20\u7edf\u6d4f\u89c8\u5668\u7684\u652f\u6301&#8211;\u901a\u8fc7 <code>nomodule<\/code> \u63d0\u4f9b\u56de\u9000\u5305\u6765\u670d\u52a1\u4f20\u7edf\u4ee3\u7801\uff0c\u8fd9\u6837\u6211\u4eec\u5c31\u53ef\u4ee5\u907f\u514d\u964d\u4f4e\u4f7f\u7528\u73b0\u4ee3\u6d4f\u89c8\u5668\u7684\u8bbf\u95ee\u8005\u7684\u4f53\u9a8c\u3002\u5982\u679c\u4f60\u9700\u8981\u66f4\u591a\u7684\u8bf4\u670d\u529b\uff0c\u8bf7\u53c2\u8003\u300a\u8fc7\u6e21\u5230\u73b0\u4ee3JavaScript\u300b\u3002<\/p>\n<p>JavaScript\u8bed\u8a00\u5728\u4e0d\u65ad\u53d1\u5c55\uff0c\u5e73\u53f0\u5728\u4f18\u5316\u73b0\u4ee3JavaScript\u65b9\u9762\u4e5f\u4e0d\u65ad\u5b8c\u5584\u3002\u6211\u4eec\u4e0d\u5e94\u8be5\u4ee5\u6d4f\u89c8\u5668\u517c\u5bb9\u6027\u4e3a\u501f\u53e3\uff0c\u5ffd\u89c6\u6240\u6709\u5df2\u7ecf\u53d6\u5f97\u7684\u6539\u8fdb\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>https:\/\/www.zhenghao.io\/posts\/object-vs-map \u5728 Java&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2,20,3],"tags":[167,91],"class_list":["post-1450","post","type-post","status-publish","format-standard","hentry","category-all","category-frontend","category-tech","tag-map","tag-object"],"_links":{"self":[{"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=\/wp\/v2\/posts\/1450","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1450"}],"version-history":[{"count":1,"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=\/wp\/v2\/posts\/1450\/revisions"}],"predecessor-version":[{"id":1451,"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=\/wp\/v2\/posts\/1450\/revisions\/1451"}],"wp:attachment":[{"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1450"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1450"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zhuxinyong.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1450"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}