jsbase/function.call2.html at master · xiongchenf/jsbase · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
	<script>
		Function.prototype.call2 = function(context) {
		    var context = context || window; //因为传进来的context有可能是null
		    context.fn = this;
		    var args = [];
		    for (var i = 1; i < arguments.length; i++) {
		        args.push("arguments[" + i + "]"); //不这么做的话 字符串的引号会被自动去掉 变成了变量 导致报错
		    }
		    console.log(args)
		    args = args.join(",");

		    var result = eval("context.fn(" + args + ")"); //相当于执行了context.fn(arguments[1], arguments[2]);

		    delete context.fn;
		    return result; //因为有可能this函数会有返回值return
		}

		Function.prototype.call3 = function(context) {
			let args = [],
				ctx = context || window;
				ctx.fn = this;
			for (var i = 0, l = arguments.length; i < l; i++) {
				args.push("arguments["+ i +"]");
			}
			args = args.join(",");
			var res = eval("ctx.fn("+ args +")");
			delete ctx.fn;
			return res;
		}

		Function.prototype.call3 = function(obj) {
			return this.apply(obj, arguments);
		}

		function Foo(obj) {
			this.name = obj.name;
		}

		Foo.prototype.getName = function() {
			return this.name
		}

		var foo = new Foo({
			name: 'foo'
		});

		var name = foo.getName.call2({
			name: 'foo2'
		});

		console.log(name)

	</script>
</body>
</html>