92 lines
2.3 KiB
HTML
92 lines
2.3 KiB
HTML
<!DOCTYPE html>
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<html lang="en">
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<head>
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<meta charset="UTF-8">
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<meta name="viewport" content="width=device-width, initial-scale=1.0">
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<title>Document</title>
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<script>
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var a = 2
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// var obj1 = {
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// a: 1,
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// fn1: (function (a) {
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// this.a = a
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// a++
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// return function () {
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// this.a = a++
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// console.log(this)
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// console.log(a)
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// }
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// })(a)
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// }
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// var fn1 = obj1.fn1
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// var fn1=function () {
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// this.a = a++
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// console.log(this)
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// console.log(a)
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// }
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// console.log(fn1.toString())
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// fn1()
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// console.log(getA)
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// if ('a' in window) {
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// var a = ''
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// function getA(a) {
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// a = a || this.a
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// console.log(this.a)
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// }
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// getA(a)
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// }
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var c = 3
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function getC() {
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this.c++
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console.log(this,'kkkk')
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return function () {
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c = this.c * 2
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console.log(c)
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}
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}
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var obj3 = {
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c: 2,
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getC: (function () {
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this.c -= 1 //win.c-1 win.c=2
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console.log(this.c, this,'sss')
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return this.getC //obj3.getc=win.getc
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})()
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}
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// var a=obj3.getC()
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// a()
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// obj3.getC()()
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getC() //win.c++ =>win.c=3
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console.log(obj3.getC.toString(),"aaaaaaa")
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obj3.getC()
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// console.log(obj3.c,window.c)
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var f3=obj3.getC;
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f3()
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// console.log(window.c)
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// console.log(obj3.c)
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//step1 立即执行函数 => this 指向window win.c-1 -> win.c=2
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//step2 getC() this.c -=> win.c++ =>2+1 =>3
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//step3 obj3.getC() step1中 obj3.getc= win.getc 所以就是执行win.getc
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// 即 winc++ win.c=3
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//obj3.getc时 this指向的是obj3，this.c操作的是obj3.c , 所以obj3.c 也+1等于3
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//step4 f3本身等于win.getc函数， 执行f3() 即执行 win.getc() =>win.c++ win.c=4
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</script>
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</head>
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<body>
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</body>
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</html> |