js源码（apply）：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<script>
function demo() {
console.log(this);
name = "2";
}
var obj = {
name: '1',
age: 2,
}
Function.prototype.myApply = function () {
var target = arguments[0] || window;
var _arg = arguments[1];
target.fn = this;
target.fn(..._arg);
}
demo.myApply(obj, [1, 2])
</script>
</body>
</html>