javascript小知识1 this的用法

函数的应用：

 1 <!DOCTYPE html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>Document</title>
 6 </head>
 7 <body>
 8 <script>
 9 function f(){
10     alert(this.x);
11 }
12 var x = 1;
13 var a = {
14     x :2
15 }
16 a.f2 = f;
17 var cc = a.f2()
18 console.log(cc)
19 </script>    
20 </body>
21 </html>

你猜 cc 是多少，是2；

再看一个例子：

 1 <!DOCTYPE html>
 2 <html lang="en">
 3 <head>
 4     <meta charset="UTF-8">
 5     <title>Document</title>
 6 </head>
 7 <body>
 8 <script>
 9 
10 var x = 1;
11 var a = {
12     x: 2,
13     fn: function() {
14         return (this.x)
15     }
16 }
17 var b = {
18     x: 3
19 }
20 q = a.fn();
21 p = a.fn;
22 q1 = p();
23 b.f2 = a.fn;
24 q3 = b.f2();
25 q5 = (b.f2)();
26 d = b.f2;
27 q4 = d();
28 console.log("q" + "~~~~" + q)
29 console.log("q1" + "~~~~" + q1)
30 console.log("q3" + "~~~~" + q3)
31 console.log("q4" + "~~~~" + q4)
32 console.log("q5" + "~~~~" + q5)
33 </script>    
34 </body>
35 </html>

注意q3与q5这俩结果是一样的；

坚持下去就能成功