js closure and prototype
js闭包 和 prototype
function test(){
var p=200;
function q(){
return p++;
}
return q;
}
var s = test();
alert(s());
alert(s());闭包： 在外部访问函数内部的变量：通过函数内部的函数，return 出 函数内部的变量
原型链继承：
<script type="text/javascript">
//定义一个people类，包括eye和hand两个属性，和 run 的方法。
function people(ec,hc){
this.eye = ec;
this.hand = hc;
}
people.prototype.run = function(){
console.log("人类用" + this.hand + "的腿跑步");
}
//定义chin类，调用people 的 call 方法，继承people的 eye 和 hand 属性。
function chin(ec,hc){
people.call(this,ec,hc);
}
//创造people类的原型副本（此时该原型副本的构造方法是指向people的，所以需要修正该构造方法，改成chin）
var _prototype = Object.create(people.prototype);
_prototype.constructor = chin;
//把chin的原型赋值给 _prototype 。此时 chin 即继承了people的 run方法。但是没有改变people的原型。
chin.prototype = _prototype;
//给chin类增加一个 sw方法。
chin.prototype.sw = function(){
console.log("中国人游泳很厉害");
}
var s = new chin("黑眼睛","黄皮肤");
console.log(s);
console.log(s.eye);
console.log(s.run());
console.log(s.sw());
var p = new people("蓝眼睛","黑皮肤");
console.log(p);
</script>结果如下：
call：
function a(data){
alert(this.q + data);
}
var s = {
q:100
}
//call的第一个参数是 this，当传入 s 时，即把this 改成了 s ，可以访问 s 内部的变量q 。
a.call(s, 1);结果 alert 101
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
What should I do if I encounter garbled code printing for front-end thermal paper receipts?
Apr 04, 2025 pm 02:42 PM
Frequently Asked Questions and Solutions for Front-end Thermal Paper Ticket Printing In Front-end Development, Ticket Printing is a common requirement. However, many developers are implementing...
Demystifying JavaScript: What It Does and Why It Matters
Apr 09, 2025 am 12:07 AM
JavaScript is the cornerstone of modern web development, and its main functions include event-driven programming, dynamic content generation and asynchronous programming. 1) Event-driven programming allows web pages to change dynamically according to user operations. 2) Dynamic content generation allows page content to be adjusted according to conditions. 3) Asynchronous programming ensures that the user interface is not blocked. JavaScript is widely used in web interaction, single-page application and server-side development, greatly improving the flexibility of user experience and cross-platform development.
Who gets paid more Python or JavaScript?
Apr 04, 2025 am 12:09 AM
There is no absolute salary for Python and JavaScript developers, depending on skills and industry needs. 1. Python may be paid more in data science and machine learning. 2. JavaScript has great demand in front-end and full-stack development, and its salary is also considerable. 3. Influencing factors include experience, geographical location, company size and specific skills.
How to achieve parallax scrolling and element animation effects, like Shiseido's official website?
or:
How can we achieve the animation effect accompanied by page scrolling like Shiseido's official website?
Apr 04, 2025 pm 05:36 PM
Discussion on the realization of parallax scrolling and element animation effects in this article will explore how to achieve similar to Shiseido official website (https://www.shiseido.co.jp/sb/wonderland/)...
The Evolution of JavaScript: Current Trends and Future Prospects
Apr 10, 2025 am 09:33 AM
The latest trends in JavaScript include the rise of TypeScript, the popularity of modern frameworks and libraries, and the application of WebAssembly. Future prospects cover more powerful type systems, the development of server-side JavaScript, the expansion of artificial intelligence and machine learning, and the potential of IoT and edge computing.
Is JavaScript hard to learn?
Apr 03, 2025 am 12:20 AM
Learning JavaScript is not difficult, but it is challenging. 1) Understand basic concepts such as variables, data types, functions, etc. 2) Master asynchronous programming and implement it through event loops. 3) Use DOM operations and Promise to handle asynchronous requests. 4) Avoid common mistakes and use debugging techniques. 5) Optimize performance and follow best practices.
How to merge array elements with the same ID into one object using JavaScript?
Apr 04, 2025 pm 05:09 PM
How to merge array elements with the same ID into one object in JavaScript? When processing data, we often encounter the need to have the same ID...
Zustand asynchronous operation: How to ensure the latest state obtained by useStore?
Apr 04, 2025 pm 02:09 PM
Data update problems in zustand asynchronous operations. When using the zustand state management library, you often encounter the problem of data updates that cause asynchronous operations to be untimely. �...
