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手写New.html
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手写New.html
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<!DOCTYPE html>
<html lang="en">
<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>TEST</title>
<style>
body {
padding: 16px 32px;
}
pre {
padding: 16px;
line-height: 1.5;
background-color: #f5f5f5;
}
</style>
</head>
<body>
<H3>1. 实现一个new操作符</H3>
<pre>
function New() {
var obj = {};
var constructor = Array.prototype.shift.call(arguments);
if (typeof constructor !== "function") {
return console.warn(`${constructor} is not a constructor`);
}
obj.__proto__ = constructor.prototype;
var ret = constructor.apply(obj, arguments);
if (typeof ret === "function" || (typeof ret === "object" && ret !== null)) {
return ret;
}
return obj;
}
console.log('============== 测试 ===============')
function A() {
console.log(...arguments);
}
const instance = New(A, "测试", 23233);
console.log(instance, instance instanceof A);
</pre>
<script>
// 1. 实现一个new操作符
function New() {
var obj = {};
var constructor = Array.prototype.shift.call(arguments);
if (typeof constructor !== "function") {
return console.warn(`${constructor} is not a constructor`);
}
obj.__proto__ = constructor.prototype;
var ret = constructor.apply(obj, arguments);
if (typeof ret === "function" || (typeof ret === "object" && ret !== null)) {
return ret;
}
return obj;
}
console.log('============== 测试 ===============')
function A() {
console.log(...arguments);
}
const instance = New(A, "测试", 23233);
console.log(instance, instance instanceof A);
</script>
</body>
</html>