<!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);