更新

2021-05-11 11:33:55 +08:00
parent 011d9328b0
commit c5f18c6051
32 changed files with 2011 additions and 26 deletions
--- a/zuoye/js/a
+++ b/zuoye/js/a
@@ -0,0 +1,92 @@
+<!DOCTYPE html>
+<html lang="en">
+
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Document</title>
+    <script>
+        var a = 2
+        // var obj1 = {
+        //     a: 1,
+        //     fn1: (function (a) {
+        //         this.a = a
+        //         a++
+        //         return function () {
+        //             this.a = a++
+        //             console.log(this)
+        //             console.log(a)
+        //         }
+
+        //     })(a)
+
+        // }
+        // var fn1 = obj1.fn1 
+        // var fn1=function () {
+        //             this.a = a++
+        //             console.log(this)
+        //             console.log(a)
+        //         }
+
+        // console.log(fn1.toString())
+        // fn1()
+
+        // console.log(getA)
+        // if ('a' in window) {
+        //     var a = ''
+        //     function getA(a) {
+        //         a = a || this.a
+        //         console.log(this.a)
+        //     }
+        //     getA(a)
+        // }
+
+
+
+        var c = 3
+        function getC() {
+            this.c++
+            console.log(this,'kkkk')
+            return function () {
+                c = this.c * 2
+                console.log(c)
+            }
+        }
+        var obj3 = {
+            c: 2,
+            getC: (function () {
+                this.c -= 1  //win.c-1  win.c=2
+                console.log(this.c, this,'sss')
+                return this.getC  //obj3.getc=win.getc
+            })()
+
+        }
+        // var a=obj3.getC()
+        // a()
+        // obj3.getC()()
+        
+        getC() //win.c++ =>win.c=3
+
+        console.log(obj3.getC.toString(),"aaaaaaa")
+        obj3.getC()  
+        // console.log(obj3.c,window.c)
+        var f3=obj3.getC;
+        f3()
+        // console.log(window.c)
+        // console.log(obj3.c)
+
+        //step1 立即执行函数  => this 指向window win.c-1  -> win.c=2
+        //step2 getC() this.c -=> win.c++ =>2+1 =>3
+        //step3 obj3.getC()  step1中 obj3.getc= win.getc  所以就是执行win.getc 
+        // 即 winc++  win.c=3  
+        //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 
+        //step4 f3本身等于win.getc函数， 执行f3() 即执行 win.getc() =>win.c++  win.c=4
+
+    </script>
+</head>
+
+<body>
+
+</body>
+
+</html>