{"id":10006851,"date":"2022-11-17T00:01:44","date_gmt":"2022-11-16T16:01:44","guid":{"rendered":"https:\/\/ityet.com\/?p=10006851"},"modified":"2022-11-17T00:01:44","modified_gmt":"2022-11-16T16:01:44","slug":"%e3%80%8c%e5%bd%bb%e5%ba%95%e5%bc%84%e6%87%82%e3%80%8dthis%e5%85%a8%e9%9d%a2%e8%a7%a3%e6%9e%90","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10006851","title":{"rendered":"\u300c\u5f7b\u5e95\u5f04\u61c2\u300dthis\u5168\u9762\u89e3\u6790"},"content":{"rendered":"

\u5173\u4e8ethis<\/h2>\n

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this\u662f\u4ec0\u4e48<\/h3>\n

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function sayHi(context) {\n  var greeting = `hi, I'm ${sayName(context)}`\n  console.log(greeting)\n}\n\nfunction sayName(context) {\n  return context.name.toLowerCase()\n}\n\nvar me = { name: 'Winfar' }\nsayHi(me) \/\/ hi, I'm winfar<\/code><\/pre>\n
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function sayHi() {\n  var greeting = `hi, I'm ${sayName.call(this)}`\n  console.log(greeting)\n}\n\nfunction sayName() {\n  return this.name.toLowerCase()\n}\n\nvar me = { name: 'Winfar' }\nsayHi.call(me) \/\/ hi, I'm winfar\nvar you = { name: 'Jack' }\nsayHi.call(you) \/\/ hi, I'm jack<\/code><\/pre>\n
\u8fd9\u6bb5\u4ee3\u7801\u53ef\u4ee5\u5728\u4e0d\u540c\u7684\u4e0a\u4e0b\u6587\u5bf9\u8c61\u4e2d\u91cd\u590d\u4f7f\u7528 sayHi()<\/code>\u548csayName()<\/code> \u51fd\u6570\u3002<\/p>\n
\u7ed1\u5b9a\u89c4\u5219<\/h2>\n
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\u9ed8\u8ba4\u7ed1\u5b9a<\/h3>\n
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function getName() {\n    console.log(this.name)\n}\nvar name = 'winfar'\ngetName() \/\/ winfar<\/code><\/pre>\n
\u4ece\u7ed3\u679c\u53d1\u73b0 this.name<\/code> \u6307\u5411\u5168\u5c40\u53d8\u91cfname<\/code>\u3002\u8fd9\u91cc\u72ec\u7acb\u51fd\u6570\u8c03\u7528 getName()<\/code>\uff0c\u5c5e\u4e8e\u9ed8\u8ba4\u7ed1\u5b9a\u89c4\u5219\uff0cthis<\/code>\u6307\u5411\u5168\u5c40\u5bf9\u8c61 window<\/code>\uff0c\u800c\u5168\u5c40\u53d8\u91cf\u5c31\u662f\u5168\u5c40\u5bf9\u8c61\u7684\u4e00\u4e2a\u540c\u540d\u5c5e\u6027\uff0c\u6240\u4ee5\uff0cthis.name<\/code>\u7b49\u4ef7\u4e8e window.name<\/code>\u3002
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function getName() {\n  'use strict'\n    console.log(this)\n}\ngetName() \/\/ undefined<\/code><\/pre>\n
\u9690\u5f0f\u7ed1\u5b9a<\/h3>\n
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function getName() {\n    console.log(this.name)\n}\nvar name = 'winfar'\nvar obj = {\n    name: 'jack',\n    getName: getName\n}\nobj.getName() \/\/ jack<\/code><\/pre>\n
\u5982\u679c\u5bf9\u8c61\u5c5e\u6027\u5d4c\u5957\u6709\u591a\u5c42\uff0c\u88ab\u8c03\u7528\u51fd\u6570\u4e2d\u7684 this<\/code> \u53ea\u4f1a\u6307\u5411\u6700\u540e\u4e00\u5c42\u5bf9\u8c61\uff0c\u53ef\u4ee5\u7406\u89e3\u4e3a\u6307\u5411\u76f4\u63a5\u8c03\u7528\u5b83\u7684\u5bf9\u8c61\u3002<\/p>\n
function getName() {\n    console.log(this.name)\n}\nvar name = 'winfar'\nvar obj = {\n    name: 'jack',\n    bar: {\n        name: 'rose',\n        getName: getName\n    }    \n}\nobj.bar.getName() \/\/ rose<\/code><\/pre>\n
\u503c\u5f97\u6ce8\u610f\uff0c\u5355\u72ec\u5c06\u5bf9\u8c61\u4e2d\u7684\u51fd\u6570\u63d0\u53d6\u51fa\u6765\u8d4b\u503c\u65b0\u53d8\u91cf\uff0c\u518d\u6267\u884c\u8fd9\u4e2a\u5f15\u7528\u53d8\u91cf\uff0cthis<\/code> \u7684\u9690\u5f0f\u6a21\u5f0f\u4f1a\u4e22\u5931\u3002<\/p>\n
function getName() {\n    console.log(this.name)\n}\nvar name = 'winfar'\nvar obj = {\n    name: 'jack',\n    getName: getName\n}\nvar bar = obj.getName\nbar() \/\/ winfar<\/code><\/pre>\n
bar<\/code>\u662f obj.getName<\/code>\u7684\u4e00\u4e2a\u5f15\u7528\uff0c\u5b9e\u9645\u4e0a\u5b83\u5f15\u7528\u7684\u662f getName<\/code> \u51fd\u6570\u672c\u8eab\uff0c\u6b64\u65f6bar()<\/code>\u662f\u5728\u4e0d\u5e26\u4efb\u4f55\u4fee\u9970\uff08\u4e0a\u4e0b\u6587\u5bf9\u8c61\uff09\u7684\u51fd\u6570\u8c03\u7528\uff0c\u8fd9\u91cc\u5e94\u7528\u4e86\u9ed8\u8ba4\u7ed1\u5b9a\u89c4\u5219\u3002
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function getName() {\n    console.log(this.name)\n}\nvar name = 'winfar'\nvar obj = {\n    name: 'jack',\n    getName: getName\n}\nfunction emitFn(fn) {\n    fn()\n}\nemitFn(obj.getName) \/\/ winfar\nsetTimeout(obj.getName) \/\/ winfar<\/code><\/pre>\n
\u4e0d\u7ba1\u6211\u4eec\u5c06\u56de\u8c03\u51fd\u6570\u4f20\u5165\u81ea\u5b9a\u4e49\u51fd\u6570 emitFn<\/code>\uff0c\u8fd8\u662f\u5185\u7f6e\u51fd\u6570 setTimeout<\/code>\uff0c\u90fd\u662f\u5e94\u7528\u9ed8\u8ba4\u7ed1\u5b9a\u89c4\u5219\uff0c\u56de\u8c03\u51fd\u6570\u4e2d\u7684 this<\/code>\u90fd\u662f\u6307\u5411\u5168\u5c40\u5bf9\u8c61\u3002<\/p>\n
    \n
  • \u5728emitFn<\/code>\u4e2d\uff0cfn<\/code>\u53c2\u6570\u662fgetName<\/code>\u51fd\u6570\u7684\u4e00\u4e2a\u5f15\u7528\uff0cfn()<\/code>\u4e0d\u5e26\u4e0a\u4e0b\u6587\u5bf9\u8c61\u7684\u51fd\u6570\u8c03\u7528\u65b9\u5f0f\u3002<\/li>\n
  • \u5728setTimeout<\/code>\u5185\u7f6e\u51fd\u6570\u7684\u5b9e\u73b0\uff0c\u4f2a\u4ee3\u7801\u7c7b\u4f3c function setTimeout(fn, delay) {fn()}<\/code>\uff0cfn()<\/code>\u4e5f\u662f\u6ca1\u6709\u4e0a\u4e0b\u6587\u5bf9\u8c61\u8c03\u7528\u3002<\/li>\n<\/ul>\n
    \u4e8e\u662f\u6211\u4eec\u53ef\u4ee5\u603b\u7ed3\uff0cobj.[xxx].bar.getName()<\/code>\u5f62\u5f0f\u8c03\u7528\uff0cgetName<\/code>\u4e2dthis<\/code>\u90fd\u6307\u5411 bar<\/code>\u5bf9\u8c61\u3002\u5982\u679c\u662f\u5355\u72ec getName()<\/code>\u5f62\u5f0f\u8c03\u7528\uff0cthis<\/code>\u6307\u5411\u5168\u5c40\u5bf9\u8c61\u3002<\/p>\n
    \u663e\u5f0f\u7ed1\u5b9a<\/h3>\n
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    JavaScript\u63d0\u4f9b\u4e86bind<\/code>\u3001call<\/code>\u548capply<\/code>\u51fd\u6570\u4e0a\u7684\u539f\u578b\u65b9\u6cd5\u53ef\u4ee5\u5f3a\u5236\u5c06\u67d0\u4e2a\u5bf9\u8c61\u7ed1\u5b9a\u5230this<\/code>\u3002<\/p>\n
    function getName() {\n    console.log(this.name)\n}\nvar name = 'winfar'\nvar obj = {\n    name: 'jack',\n    getName: getName\n}\nvar bar = {\n    name: 'rose'\n}\nobj.getName.call(bar) \/\/ rose\nobj.getName.apply(bar) \/\/ rose\n\nvar bar = obj.getName.bind(bar)\nbar() \/\/ rose<\/code><\/pre>\n
    \u5982\u679c\u4f20\u5165\u7684\u662f\u4e00\u4e2a\u539f\u59cb\u503c\uff08String<\/code>\u3001Boolean<\/code>\u6216\u8005Number<\/code>\uff09\u5f53\u505a this<\/code>\u7684\u7ed1\u5b9a\u5bf9\u8c61\uff0c\u8fd9\u4e2a\u539f\u59cb\u503c\u4f1a\u88ab\u8f6c\u6362\u6210\u5b83\u7684\u5bf9\u8c61\u5f62\u5f0f\uff0c\u4e5f\u5c31\u662fnew String()<\/code>\u3001new Boolean()<\/code>\u6216\u8005new Number()<\/code>\uff0c\u8fd9\u901a\u5e38\u88ab\u79f0\u4e3a\u201d\u88c5\u7bb1\u201c\u3002<\/p>\n
    function getName() {\n    console.log(this)\n}\nvar obj = {\n    getName: getName\n}\nobj.getName.call(1) \/\/ Number\u00a0{1}\nobj.getName.call('winfar') \/\/ String\u00a0{'winfar'}\nobj.getName.call(true) \/\/ Boolean\u00a0{true}<\/code><\/pre>\n
    \u5f53\u4f20\u5165\u7684\u662f null<\/code>\u6216\u8005undefined<\/code>\uff0cthis<\/code>\u7ed1\u5b9a\u5230\u5168\u5c40\u5bf9\u8c61\u3002<\/p>\n
    obj.getName.call(undefined) \/\/ Window\nobj.getName.call(null) \/\/ Window<\/code><\/pre>\n
    new\u7ed1\u5b9a<\/h3>\n
    \u5728JavaScript\u4e2d\uff0c\u4f7f\u7528new<\/code>\u6267\u884c\u4e00\u4e2a\u51fd\u6570\uff08\u6784\u9020\u51fd\u6570\uff09\uff0c\u4e00\u822c\u7684\uff0c\u51fd\u6570\u4e2d\u7684this<\/code>\u4f1a\u6307\u5411\u751f\u6210\u7684\u5b9e\u4f8b\u5bf9\u8c61\u3002<\/p>\n
    function GetName() {\n    console.log(this)\n}\nnew GetName() \/\/ GetName\u00a0{}<\/code><\/pre>\n
    \u4e3a\u4ec0\u4e48\u8bf4\u201d\u4e00\u822c\u201c\u60c5\u51b5\u4e0b\u5462\uff1f\u56e0\u4e3a\u5f53\u6784\u9020\u8fd4\u56de\u6570\u636e\u4e3a\u5f15\u7528\u5bf9\u8c61\u65f6\uff0cthis<\/code>\u6307\u5411\u8fd4\u56de\u7684\u5bf9\u8c61\u672c\u8eab\u3002<\/p>\n
    function GetName() {\n    console.log(this)\n    return {name: 'winfar'}\n}\nnew GetName() \/\/ {name: 'winfar'}<\/code><\/pre>\n
    \u4e0b\u9762\u6765\u6a21\u62df\u5b9e\u73b0new<\/code>\u64cd\u4f5c\u7b26<\/p>\n
      \n
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    • \u5176\u6b21\u8c03\u7528\u6784\u9020\u51fd\u6570\uff0c\u5e76\u5c06this<\/code>\u7ed1\u5b9a\u5230\u8be5\u5bf9\u8c61\uff1b<\/li>\n
    • \n
      \u6700\u540e\u6784\u9020\u51fd\u6570\u6267\u884c\u8fd4\u56de\u503c\uff0c\u5982\u679c\u662f\u975e\u5f15\u7528\u7c7b\u578b\uff0c\u8fd4\u56de\u521b\u5efa\u7684\u5bf9\u8c61\uff0c\u5426\u5219\u76f4\u63a5\u8fd4\u56de\u6784\u9020\u51fd\u6570\u7684\u8fd4\u56de\u503c\uff1b<\/p>\n
      function myNew(Fn) {\n\/\/ ES6 \u4e2d new.target \u6307\u5411\u6784\u9020\u51fd\u6570\nmyNew.target = Fn\n\n\/\/ const obj = {}\n\/\/ obj.__proto__=Fn.prototype\n\/\/ \u521b\u5efa\u4e00\u4e2a\u5bf9\u8c61\uff0c\u5bf9\u8c61\u539f\u578b\u6307\u5411\u6784\u9020\u51fd\u6570\u539f\u578b\nconst obj = Object.create(Fn.prototype)\n\n\/\/ \u8c03\u7528\u6784\u9020\u51fd\u6570\uff0c\u5e76\u5c06this\u7ed1\u5b9a\u5230\u8be5\u5bf9\u8c61\nconst result = Fn.apply(obj, [...arguments])\n\n\/\/ \u6784\u9020\u51fd\u6570\u6267\u884c\u8fd4\u56de\u503c\uff0c\u5982\u679c\u662f\u975e\u5f15\u7528\u7c7b\u578b\uff0c\u8fd4\u56de\u521b\u5efa\u7684\u5bf9\u8c61\uff0c\u5426\u5219\u76f4\u63a5\u8fd4\u56de\u6784\u9020\u51fd\u6570\u7684\u8fd4\u56de\u503c\nconst type = typeof result\nreturn (type === 'object' && result !== null) || type === 'function' ? res : obj\n}<\/code><\/pre>\n
      \u89c4\u5219\u4f18\u5148\u7ea7<\/h2>\n
      \u4ee5\u4e0a\u6211\u4eec\u4e86\u89e3\u4e864\u79cdthis<\/code>\u7684\u7ed1\u5b9a\u89c4\u5219\uff0c\u90a3\u4e48\u5b83\u4eec\u7684\u4f18\u5148\u7ea7\u53c8\u5982\u4f55\u5462\uff1f
      \u9996\u5148\u6765\u770b\u9690\u5f0f\u7ed1\u5b9a\u548c\u663e\u793a\u7ed1\u5b9a\u7684\u4f18\u5148\u7ea7<\/p>\n
      function getName() {\n  console.log(this.name)\n}\nvar obj = {\n  name: 'winfar',\n  getName: getName\n}\nvar bar = {\n  name: 'jack',\n  getName: getName\n}\nobj.getName() \/\/ winfar\nbar.getName() \/\/ jack\nobj.getName.call(bar) \/\/ jack\nbar.getName.call(obj) \/\/ winfar<\/code><\/pre>\n
      \u53ef\u4ee5\u770b\u5230\u663e\u793a\u7ed1\u5b9a\u7684\u4f18\u5148\u7ea7\u6bd4\u9690\u5f0f\u7ed1\u5b9a\u66f4\u9ad8\u3002
      \u518d\u6765\u6bd4\u8f83\u9690\u5f0f\u7ed1\u5b9a\u4e0enew\u7ed1\u5b9a\u7684\u4f18\u5148\u7ea7<\/p>\n
      function getName(name) {\n  this.name = name\n}\nvar obj = {\n  getName: getName\n}\nobj.getName('winfar')\nvar bar = new obj.getName('jack')\nconsole.log(bar.name) \/\/ jack\nconsole.log(obj.name) \/\/ winfar<\/code><\/pre>\n
      new\u7ed1\u5b9a\u6bd4\u9690\u5f0f\u7ed1\u5b9a\u4f18\u5148\u7ea7\u9ad8\u3002
      \u663e\u5f0f\u7ed1\u5b9a\u4e0enew\u7ed1\u5b9a\u4f18\u5148\u7ea7\u53c8\u5982\u4f55\u5462\uff1f
      new<\/code>\u64cd\u4f5c\u7b26\u4e0ecall<\/code>\u3001apply<\/code>\u65e0\u6cd5\u4e00\u8d77\u4f7f\u7528\uff0c\u6bd4\u5982new obj.getName.call('winfar')<\/code>\u3002\u4f46\u662fbind<\/code>\u53ef\u4ee5<\/p>\n
      function getName(name) {\n  this.name = name\n}\nvar obj = {}\nvar fn = getName.bind(obj)\nfn('winfar')\nconsole.log(obj.name) \/\/ winfar\nvar bar = new fn('jack')\nconsole.log(bar.name) \/\/ jack\nconsole.log(obj.name) \/\/ winfar<\/code><\/pre>\n
      \u7531\u4e0a\u9762\u53ef\u4ee5\u770b\u51fa\uff0cbind<\/code>\u5c06this<\/code>\u7ed1\u5b9a\u5230obj<\/code>\u5bf9\u8c61\u4e0a\uff0c\u5e76\u7ed9obj<\/code>\u5bf9\u8c61\u6dfb\u52a0\u5c5e\u6027name<\/code>\uff0c\u5728new<\/code>\u6267\u884c\u51fd\u6570\u540ethis<\/code>\u6ca1\u6709\u6267\u884cobj<\/code>\u5bf9\u8c61\uff0c\u800c\u662f\u65b0\u751f\u6210\u4e00\u4e2a\u5bf9\u8c61\u5e76\u6dfb\u52a0name<\/code>\u5c5e\u6027\u3002\u4ece\u800c\u5f97\u51fanew<\/code>\u7ed1\u5b9a\u4f18\u5148\u7ea7\u6bd4\u663e\u793a\u7ed1\u5b9a\u9ad8\u3002
      \u7efc\u4e0a\u53ef\u77e5\uff0cthis<\/code>\u76844\u79cd\u7ed1\u5b9a\u4f18\u5148\u7ea7\u987a\u5e8f\u4f9d\u6b21\u4e3a new\u7ed1\u5b9a > \u663e\u793a\u7ed1\u5b9a > \u9690\u5f0f\u7ed1\u5b9a > \u9ed8\u8ba4\u7ed1\u5b9a\u3002
      \"\"<\/p>\n
      \u7bad\u5934\u51fd\u6570\u4e2dthis<\/h2>\n
      \u5728ES6\u4e2d\u4f7f\u7528\u7bad\u5934=><\/code>\u51fd\u6570\u7b80\u5316function<\/code>\u5173\u952e\u5b57\uff0c\u5b83\u4e0d\u9002\u7528\u4e0a\u9762this<\/code>\u7684\u56db\u79cd\u7ed1\u5b9a\u89c4\u5219\uff0c\u8fd9\u91cc\u6211\u4eec\u987a\u4fbf\u56de\u987e\u4e00\u4e0b\u7bad\u5934\u51fd\u6570\u7684\u51e0\u4e2a\u4f7f\u7528\u6ce8\u610f\u70b9\u3002
      \uff081\uff09\u7bad\u5934\u51fd\u6570\u6ca1\u6709\u81ea\u5df1\u7684this<\/code>\u5bf9\u8c61\u3002
      \uff082\uff09\u4e0d\u53ef\u4ee5\u5f53\u4f5c\u6784\u9020\u51fd\u6570\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u4e0d\u53ef\u4ee5\u5bf9\u7bad\u5934\u51fd\u6570\u4f7f\u7528new<\/code>\u547d\u4ee4\uff0c\u5426\u5219\u4f1a\u629b\u51fa\u4e00\u4e2a\u9519\u8bef\u3002
      \uff083\uff09\u4e0d\u53ef\u4ee5\u4f7f\u7528arguments<\/code>\u5bf9\u8c61\uff0c\u8be5\u5bf9\u8c61\u5728\u51fd\u6570\u4f53\u5185\u4e0d\u5b58\u5728\u3002\u5982\u679c\u8981\u7528\uff0c\u53ef\u4ee5\u7528 rest<\/code> \u53c2\u6570\u4ee3\u66ff\u3002
      \uff084\uff09\u4e0d\u53ef\u4ee5\u4f7f\u7528yield<\/code>\u547d\u4ee4\uff0c\u56e0\u6b64\u7bad\u5934\u51fd\u6570\u4e0d\u80fd\u7528\u4f5c Generator<\/code> \u51fd\u6570\u3002
      \u9488\u5bf9\u4e8e\u7bad\u5934\u51fd\u6570\u6ca1\u6709\u81ea\u5df1\u7684this<\/code>\u5bf9\u8c61\uff0c\u6839\u636e\u5916\u5c42\u4f5c\u7528\u57df\uff08\u51fd\u6570\u6216\u8005\u5168\u5c40\uff09\u6765\u51b3\u5b9athis<\/code>\uff0c\u6765\u770b\u4e0b\u9762\u8fd9\u4e2a\u4f8b\u5b50\u3002<\/p>\n
      function getName() {\n  return () => {\n      console.log(this.name)\n  }\n}\nvar name = 'winfar'\nvar obj = {\n  name: 'jack'\n}\nvar bar = {\n  name: 'rose'\n}\nvar fn = getName.call(obj)\nfn.call(bar) \/\/ jack<\/code><\/pre>\n
      getName<\/code>\u51fd\u6570\u5185\u90e8\u521b\u5efa\u7684\u7bad\u5934\u51fd\u6570\u4f1a\u6355\u83b7\u8c03\u7528\u65f6getName<\/code>\u7684this<\/code>\uff0c\u7531\u4e8egetName<\/code>\u5728\u8c03\u7528\u65f6this<\/code>\u7ed1\u5b9a\u4e86obj<\/code>\u5bf9\u8c61\uff0c\u7bad\u5934\u51fd\u6570\u4e2d\u7684this<\/code>\u7ed1\u5b9aobj<\/code>\u5bf9\u8c61\uff0c\u5373\u4f7f\u540e\u9762\u663e\u793a\u7ed1\u5b9a\u5176\u4ed6\u5bf9\u8c61\u6267\u884c\u4e5f\u4e0d\u80fd\u6539\u53d8\u5b83\u7684\u6307\u5411\u3002
      \u8fd8\u6709\u4e00\u70b9\u503c\u5f97\u6ce8\u610f\u7684\uff0c\u5982\u679c\u7bad\u5934\u51fd\u6570\u5916\u5c42\u4f5c\u7528\u57dfthis<\/code>\u6307\u5411\u662f\u53d8\u5316\u7684\uff0c\u7bad\u5934\u51fd\u6570\u5185\u90e8this<\/code>\u4e5f\u4f1a\u8ddf\u7740\u53d8\u5316\u3002<\/p>\n
      function getName() {\n  return () => {\n      console.log(this.name)\n  }\n}\nvar name = 'winfar'\nvar obj = {\n  name: 'jack'\n}\nvar bar = {\n  name: 'rose'\n}\n\nvar fn = getName.call(obj)\nfn() \/\/ jack\nvar fn1 = getName.call(bar)\nfn1() \/\/ rose<\/code><\/pre>\n
      \u7b2c\u4e00\u6b21getName<\/code>\u51fd\u6570\u4e2dthis<\/code>\u7ed1\u5b9aobj<\/code>\uff0c\u5185\u90e8\u7bad\u5934\u51fd\u6570\u7684this<\/code>\u7ee7\u627f\u5916\u5c42\u4f5c\u7528\u57dfthis<\/code>\uff0cfn<\/code>\u662f\u5185\u90e8\u7bad\u5934\u51fd\u6570\u5f15\u7528\uff0c\u5728\u6267\u884cfn<\/code>\u65f6\uff0c\u8fd9\u91cc\u662f\u9ed8\u8ba4\u7ed1\u5b9a\uff0c\u4f46\u662f\u4e0d\u9002\u7528\u7bad\u5934\u51fd\u6570\uff0c\u7bad\u5934\u51fd\u6570\u5185\u90e8this<\/code>\u4ecd\u662f\u5916\u5c42this<\/code>\u3002
      \u540c\u7406\uff0c\u7b2c\u4e8c\u6b21getName<\/code>\u51fd\u6570\u4e2dthis<\/code>\u7ed1\u5b9abar<\/code>\uff0cfn1<\/code>\u7bad\u5934\u51fd\u6570\u5185\u90e8this<\/code>\u4e5f\u662f\u7ee7\u627f\u4e8e\u5916\u5c42this<\/code>\u3002<\/p>\n
      this\u6307\u5411\u5224\u65ad\u6d41\u7a0b<\/h2>\n
      \u6211\u4eec\u5df2\u7ecf\u77e5\u9053\u4e86this<\/code>\u6307\u5411\u7684\u56db\u79cd\u7ed1\u5b9a\u89c4\u5219\u548c\u7bad\u5934\u51fd\u6570\u4e2d\u7684this<\/code>\u7ed1\u5b9a\u3002\u73b0\u5728\u53ef\u4ee5\u4ece\u6574\u4f53\u6765\u770bthis<\/code>\u6307\u5411\u7684\u5224\u65ad\u6d41\u7a0b<\/p>\n<\/li>\n
    • \u7bad\u5934\u51fd\u6570\u5185\u7684this<\/code>\u7ee7\u627f\u5916\u5c42\u4f5c\u7528\u57df\u7684this<\/code>\uff1b<\/li>\n
    • \u51fd\u6570\u901a\u8fc7new<\/code>\u8c03\u7528\uff0cthis<\/code>\u7ed1\u5b9a\u65b0\u521b\u5efa\u7684\u5bf9\u8c61\uff1b<\/li>\n
    • \u51fd\u6570\u901a\u8fc7bind<\/code>\u7ed1\u5b9a\u6216\u8005call<\/code>`apply\u8c03\u7528\uff0cthis\u6307\u5411\u88ab\u7ed1\u5b9a\u5bf9\u8c61\uff08\u975e<\/code>undefined\u3001<\/code>null`\uff09\uff1b<\/li>\n
    • \u51fd\u6570\u901a\u8fc7\u67d0\u4e2a\u4e0a\u4e0b\u6587\u5bf9\u8c61\u8c03\u7528\uff0cthis<\/code>\u7ed1\u5b9a\u8be5\u4e0a\u4e0b\u6587\u5bf9\u8c61\uff1b<\/li>\n
    • \u5728\u4e25\u683c\u6a21\u5f0f\u4e0b\uff0cthis<\/code>\u6307\u5411undefined<\/code>\uff0c\u5426\u5219\u7ed1\u5b9a\u5230Window<\/code>\u5bf9\u8c61\uff1b<\/li>\n<\/ul>\n
      \"\"<\/p>\n
      \u5206\u6790\u4e00\u9053\u7efc\u5408\u9898<\/h2>\n
      \u5b9e\u8df5\u662f\u68c0\u9a8c\u771f\u7406\u7684\u552f\u4e00\u6807\u51c6\uff0c\u63a5\u4e0b\u6211\u4eec\u518d\u6765\u770b\u4e00\u9053\u7efc\u5408\u9898\u68c0\u9a8c\u4e00\u4e0b\u6211\u4eec\u7684\u5b66\u4e60\u6210\u679c\u3002<\/p>\n
      var age = 1\nvar obj = {\n    age: 2,\n    getAge: function() {\n        var age = 3\n        this.age *= 2\n        age *= 3\n        \n        return () => {\n            var g = this.age\n            this.age *= 4\n            console.log(g) \n            age *= 5\n            console.log(age)\n        }\n    } \n}\nvar fn = obj.getAge\nvar bar = fn.call(null)\nbar.call(obj)\nconsole.log(window.age)<\/code><\/pre>\n
      fn<\/code>\u662fgetAge<\/code>\u51fd\u6570\u5f15\u7528\uff0cfn.call(null)<\/code>\u5c06\u51fd\u6570getAge<\/code>\u7684this<\/code>\u663e\u5f0f\u7ed1\u5b9a\u5230window<\/code>\u5bf9\u8c61\uff0c\u6b64\u65f6\u4f5c\u7528\u57df\u4e2d\u53d8\u91cf\u5206\u5e03\u60c5\u51b5<\/p>\n
      \/\/ \u5168\u5c40\u4f5c\u7528\u57df\nthis = window\nage = 1\n\n\/\/ getAge\u51fd\u6570\u4f5c\u7528\u57df\nthis = window\nage = 3<\/code><\/pre>\n
      this.age *= 2<\/code>\u6539\u53d8\u7684\u662f\u5168\u5c40\u7684age<\/code>\uff0cage *= 3<\/code>\u6539\u53d8\u7684\u662fgetAge<\/code>\u51fd\u6570\u5c40\u90e8\u53d8\u91cfage<\/code><\/p>\n
      \/\/ \u5168\u5c40\u4f5c\u7528\u57df\nthis = window\nage = 1 * 2 = 2\n\n\/\/ getAge\u51fd\u6570\u4f5c\u7528\u57df\nthis = window\nage = 3 * 3 = 9<\/code><\/pre>\n
      getAge<\/code>\u51fd\u6570\u4e2d\u7684\u7bad\u5934\u51fd\u6570\u4e2dthis<\/code>\u7ee7\u627fgetAge<\/code>\u51fd\u6570this<\/code>\uff0cbar<\/code>\u662f\u7bad\u5934\u51fd\u6570\u7684\u5f15\u7528\uff0cbar.call(obj)<\/code>\u867d\u7136\u5c06this<\/code>\u663e\u793a\u7ed1\u5b9a\u5230obj<\/code>\uff0c\u4f46\u662f\u7bad\u5934\u51fd\u6570\u4e0d\u9002\u7528\u8be5\u7ed1\u5b9a\u539f\u5219\uff0c\u4f9d\u65e7\u662fgetAge<\/code>\u51fd\u6570this<\/code>\u3002<\/p>\n
      \/\/ \u5168\u5c40\u4f5c\u7528\u57df\nthis = window\nage = 2\n\n\/\/ getAge\u51fd\u6570\u4f5c\u7528\u57df\nthis = window\nage = 9\n\n\/\/ \u7bad\u5934\u51fd\u6570\u4f5c\u7528\u57df\nthis = window\ng = 2<\/code><\/pre>\n
      \u7bad\u5934\u51fd\u6570\u4e2dthis.age *= 4<\/code>\u6539\u53d8\u7684\u5168\u5c40age<\/code>\uff0c\u7bad\u5934\u51fd\u6570\u5185\u6ca1\u6709\u58f0\u660e\u81ea\u5df1\u7684\u73af\u5883\u53d8\u91cfage<\/code>\uff0c\u7ee7\u627fgetAge<\/code>\u51fd\u6570\u53d8\u91cf\uff0cage *= 5<\/code>\u6539\u53d8\u7684\u662f\u5916\u5c42\u51fd\u6570\u53d8\u91cf<\/p>\n
      \/\/ \u5168\u5c40\u4f5c\u7528\u57df\nthis = window\nage = 2 * 4 = 8\n\n\/\/ getAge\u51fd\u6570\u4f5c\u7528\u57df\nthis = window\nage = 9 * 5 = 45\n\n\/\/ \u7bad\u5934\u51fd\u6570\u4f5c\u7528\u57df\nthis = window\ng = 2<\/code><\/pre>\n
      \u6240\u4ee5\uff0c\u6700\u7ec8\u7ed3\u679c\u662f 2 45 8\u3002\u8fd8\u6709\u5f88\u591a\u53d8\u79cd\uff0c\u6bd4\u5982<\/p>\n
      obj.getAge().call(obj)\nconsole.log(window.age)<\/code><\/pre>\n
      \u7ed3\u679c\u53c8\u662f\u600e\u6837\u5462\uff1f\u54c8\u54c8\u54c8\uff0c\u7559\u7ed9\u5927\u5bb6\u81ea\u5df1\u601d\u8003\u4e86\u3002\u5b8c~<\/p>\n
      https:\/\/segmentfault.com\/a\/1190000042809553<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
      \u5173\u4e8ethis this\u5728JavaScript\u4e2d\u5f88\u5e38\u7528\uff0c\u5173\u4e8ethis\uff0c\u8981\u5f04\u61c2this\uff0c \u9996\u5148\u5c31\u8981\u77e5\u9053this\u662f\u4ec0 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[4],"tags":[],"class_list":["post-10006851","post","type-post","status-publish","format-standard","hentry","category-share"],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10006851","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=10006851"}],"version-history":[{"count":0,"href":"https:\/\/itmax.cn\/index.php?rest_route=\/wp\/v2\/posts\/10006851\/revisions"}],"wp:attachment":[{"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=10006851"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=10006851"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/itmax.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=10006851"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}