<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<meta http-equiv="X-UA-Compatible" content="ie=edge" />
<title>apply和call</title>
</head>
<body>
<script type="text/javascript">
function fn(n1, n2) {
return this.a + n1 + n2
}
var a = 20;
var o = {
a: 40
}
console.log(fn(10, 10))
//apply的第二个参数必须是数组
console.log(fn.apply(o, [10, 10]))
//call的参数 一个一个传递
console.log(fn.call(o, 10, 10))
</script>
</body>
</html>
模拟实现：
Function.prototype.call2 = function(context) { context.fn = this; var args = []; for(var i = 1, len = arguments.length; i < len; i++) { args.push('arguments[' + i + ']'); } eval('context.fn(' + args +')'); delete context.fn; } // 测试一下 var foo = { value: 1 }; function bar(name, age) { console.log(name) console.log(age) console.log(this.value); } bar.call2(foo, 'Cherry', 18);