Home Web Front-end JS Tutorial Multiple XMLHttpRequest objects on one page_javascript skills

Multiple XMLHttpRequest objects on one page_javascript skills

May 16, 2016 pm 07:20 PM

I just posted a post on ajacn about providing an object pool for XMLHttpRequest. Maybe it can help you, repost it as follows:

I saw some comrades on the Internet mentioned providing an object pool for Ajax's XMLHttpRequest, and also read the implementation code they gave. It didn't feel particularly ideal, so I wrote a simple JavaScript version imitating the idea of ​​ObjectPool in apache's commons.
Hope for advice:


Code
function ObjectPool(poolableObjectFactory) {                                                                                This._activePool = []; 
} 
//Lease an object from the object pool. If there is no free object currently available, create one through poolableObjectFactory 
//Since it is borrowed, remember to return it after use. !    
ObjectPool.prototype.borrowObject = function() {    
    var object = null;    
    var idlePool = this._idlePool;    
    var factory = this._poolableObjectFactory;    
    if (idlePool.length > 0) {    
        object = idlePool.pop();    
    }    
    else {    
        object = factory.makeObject();    
    }    
    if (object != null) {    
        this._activePool.push(object);    
        if (factory.activateObject) {    
            factory.activateObject(object);    
        }    
    }    
    return object;    
}    
// 归还一个对象    
ObjectPool.prototype.returnObject = function(object) {    
    function indexOf(array, object) {    
        for (var i = 0; i             if (array[i] == object) return i;    
        }    
        return -1;    
    }    
    if (object != null) {    
        var activePool = this._activePool;    
        var factory = this._poolableObjectFactory;          
        var i = indexOf(activePool, object);    
        if (i         if (factory.passivateObject) {    
            factory.passivateObject(object);    
        }           
        activePool.splice(i, 1);    
        this._idlePool.push(object);    
    }    
}    
// 返回当前激活对象的个数    
ObjectPool.prototype.getNumActive = function() {    
    return this._activePool.length;    
}    
// 返回当前空闲对象的个数    
ObjectPool.prototype.getNumIdle = function() {    
    return this._idlePool.length;    
}    
// 销毁对象池及其中的所有对象    
// 如果对象池中的对象需要析构。那么必须实现poolableObjectFactory中的destroyObject方法,同时保证ObjectPool的destroy方法在需要的时候被调用到(例如Window的unload事件中)。    
ObjectPool.prototype.destroy = function() {    
    var factory = this._poolableObjectFactory;    
    function returnObject(object) {    
        if (factory.passivateObject) {    
            factory.passivateObject(object);    
        }    
    }    
    function destroyObject(object) {    
        if (factory.destroyObject) {    
            factory.destroyObject(object);    
        }    
    }       
    var activePool = this._activePool;    
    for (var i = 0; i         var object = activePool[i];    
        returnObject(object);    
        destroyObject(object);    
    }    
    var idlePool = this._idlePool;    
    for (var i = 0; i         var object = idlePool[i];    
        destroyObject(object);    
    }    
    this._idlePool = null;     
    this._activePool = null;     
    this._poolableObjectFactory = null;    
}   

上面代码中ObjectPool的构造参数poolableObjectFactory的声明如下: 

代码
// 注意: 这只是说明,不是真正的代码!    
var PoolableObjectFactory = {           
    makeObject: function() {}, // 创建一个新的对象。(必须声明)       

    activateObject: function(object) {}, // 当一个对象被激活时(即被借出时)触发的方法。(可选)    

    passivateObject: function(object) {}, // 当一个对象被钝化时(即被归还时)触发的方法。(可选)    

    destroyObject: function(object) {} // 销毁一个对象。(Optional)                                                                                                                               makeObject: function() {                                                                                                             
if (window.ActiveXObject){
return new ActiveXObject("Microsoft.XMLHTTP");
else {           return new XMLHttpRequest();                                                          ,                                                                                              passivateObject: function(xhr)                                                                           abort(); 
 } 
}; 
var pool = new ObjectPool(factory); // Create an object pool
// ......
var xhr = pool.borrowObject(); // Get an XMLHttpRequest object
xhr.onreadystatechange = function() {                                                                                 🎜 >};
xhr.open(method, url, true); 🎜>function test_pool() { 
 var factory = { 
 counter: 0, 

 makeObject: function() { 
  return {id: this.counter};                                                   

activateObject: function(object) {
object.activated = true;
},

passivateObject: function(object) {
object.activated = false; ​​​​🎜> };    
    var pool = new ObjectPool(factory);    
    // borrowObject object1    
    var object1 = pool.borrowObject();    
    assertEquals(object1.id, 1);    
    assertTrue(object1.activated);    
    assertEquals(factory.counter, 1);    
    assertEquals(pool.getNumActive(), 1);    
    assertEquals(pool.getNumIdle(), 0);    
    // borrowObject object2    
    var object2 = pool.borrowObject();    
    assertEquals(object2.id, 2);    
    assertTrue(object2.activated);    
    assertEquals(factory.counter, 2);    
    assertEquals(pool.getNumActive(), 2);    
    assertEquals(pool.getNumIdle(), 0);    
    // borrowObject object3    
    var object3 = pool.borrowObject();    
    assertEquals(object3.id, 3);    
    assertTrue(object3.activated);    
    assertEquals(factory.counter, 3);    
    assertEquals(pool.getNumActive(), 3);    
    assertEquals(pool.getNumIdle(), 0);    
    // returnObject object2    
    pool.returnObject(object2);    
    assertFalse(object2.activated);    
    assertEquals(factory.counter, 3);    
    assertEquals(pool.getNumActive(), 2);    
    assertEquals(pool.getNumIdle(), 1);    
    // returnObject object3    
    pool.returnObject(object3);    
    assertFalse(object3.activated);    
    assertEquals(pool.getNumActive(), 1);    
    assertEquals(pool.getNumIdle(), 2);    
    // returnObject object1    
    pool.returnObject(object1);    
    assertFalse(object1.activated);    
    assertEquals(pool.getNumActive(), 0);    
    assertEquals(pool.getNumIdle(), 3);         
    // destroy the pool    
    pool.destroy();    
    assertTrue(object1.destroyed);    
    assertTrue(object2.destroyed);    
    assertTrue(object3.destroyed);    
}  

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Hot Topics

Java Tutorial
1663
14
PHP Tutorial
1264
29
C# Tutorial
1237
24
Demystifying JavaScript: What It Does and Why It Matters 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.

The Evolution of JavaScript: Current Trends and Future Prospects 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.

JavaScript Engines: Comparing Implementations JavaScript Engines: Comparing Implementations Apr 13, 2025 am 12:05 AM

Different JavaScript engines have different effects when parsing and executing JavaScript code, because the implementation principles and optimization strategies of each engine differ. 1. Lexical analysis: convert source code into lexical unit. 2. Grammar analysis: Generate an abstract syntax tree. 3. Optimization and compilation: Generate machine code through the JIT compiler. 4. Execute: Run the machine code. V8 engine optimizes through instant compilation and hidden class, SpiderMonkey uses a type inference system, resulting in different performance performance on the same code.

JavaScript: Exploring the Versatility of a Web Language JavaScript: Exploring the Versatility of a Web Language Apr 11, 2025 am 12:01 AM

JavaScript is the core language of modern web development and is widely used for its diversity and flexibility. 1) Front-end development: build dynamic web pages and single-page applications through DOM operations and modern frameworks (such as React, Vue.js, Angular). 2) Server-side development: Node.js uses a non-blocking I/O model to handle high concurrency and real-time applications. 3) Mobile and desktop application development: cross-platform development is realized through ReactNative and Electron to improve development efficiency.

Python vs. JavaScript: The Learning Curve and Ease of Use Python vs. JavaScript: The Learning Curve and Ease of Use Apr 16, 2025 am 12:12 AM

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

How to Build a Multi-Tenant SaaS Application with Next.js (Frontend Integration) How to Build a Multi-Tenant SaaS Application with Next.js (Frontend Integration) Apr 11, 2025 am 08:22 AM

This article demonstrates frontend integration with a backend secured by Permit, building a functional EdTech SaaS application using Next.js. The frontend fetches user permissions to control UI visibility and ensures API requests adhere to role-base

From C/C   to JavaScript: How It All Works From C/C to JavaScript: How It All Works Apr 14, 2025 am 12:05 AM

The shift from C/C to JavaScript requires adapting to dynamic typing, garbage collection and asynchronous programming. 1) C/C is a statically typed language that requires manual memory management, while JavaScript is dynamically typed and garbage collection is automatically processed. 2) C/C needs to be compiled into machine code, while JavaScript is an interpreted language. 3) JavaScript introduces concepts such as closures, prototype chains and Promise, which enhances flexibility and asynchronous programming capabilities.

Building a Multi-Tenant SaaS Application with Next.js (Backend Integration) Building a Multi-Tenant SaaS Application with Next.js (Backend Integration) Apr 11, 2025 am 08:23 AM

I built a functional multi-tenant SaaS application (an EdTech app) with your everyday tech tool and you can do the same. First, what’s a multi-tenant SaaS application? Multi-tenant SaaS applications let you serve multiple customers from a sing

See all articles