search
HomeWeb Front-endJS TutorialJavaScript implements cookie-based storage class instance_javascript skills

The example in this article describes the implementation of Cookie-based storage class in JavaScript. Share it with everyone for your reference. The specific analysis is as follows:

Through this JS class, you can use cookies just like using sessions, it’s very simple!

/*
 * CookieStorage.js
 * 本类实现像localStorage和sessionStorage一样的存储API
 * 不同的是,它是基于HTTP Cookies实现的.
 */
function CookieStorage(maxage, path) {
// 两个参数分别代表储存有效期和作用域
 // 获取一个储存全部cookies的对象
 var cookies = (function() {
 // 类型之前介绍的getCookies函数
  var cookies = {};
  // 该对象最终会返回
  var all = document.cookie;
  // 以大字符串的形式获取所有cookies的信息
  if (all === "")
  // 如果该属性为空白符
   return cookies;
   // 返回一个空对象
  var list = all.split("; ");
  // 分离出名/值对
  for(var i = 0; i < list.length; i++) {
  // 遍历每个cookie
   var cookie = list[i];
   var p = cookie.indexOf("=");
   // 找到第一个“=”符号
   var name = cookie.substring(0,p);
   // 获取cookie的名字
   var value = cookie.substring(p+1);
   // 获取cookie对应的值
   value = decodeURIComponent(value);
   // 对其值进行解码
   cookies[name] = value;
   // 将名值对存储到对象中
  }
  return cookies;
 }());
 // 将所有cookie的名字存储到一个数组中
 var keys = [];
 for(var key in cookies) keys.push(key);
 // 现在定义储存API公共的属性和方法
 // 储存的cookies的个数
 this.length = keys.length;
 // 返回第n个cookie的名字,如果n越界则返回null
 this.key = function(n) {
  if (n < 0 || n >= keys.length) return null;
  return keys[n];
 };
 // 返回指定名字的cookie值,如果不存在则返回null
 this.getItem = function(name){
 return cookies[name] || null;
 };
 // 储存cookie值
 this.setItem = function(key, value) {
  if (!(key in cookies)) {
  // 如果要促成的cookie还不存在
   keys.push(key);
   // 将指定的名字加入到储存所有cookie名的数组中
   this.length++;
   // cookies个数加一
  }
  // 将该名/值对数据存储到cookie对象中.
  cookies[key] = value;
  // 开始正式设置cookie.
  // 首先将要储存的cookie的值进行编码
  // 同时创建一个“名称=编码后的值”形式的字符串
  var cookie = key + "=" + encodeURIComponent(value);
  // 将cookie的属性也加入到该字符串中
  if (maxage) cookie += "; max-age=" + maxage;
  if (path) cookie += "; path=" + path;
  // 通过document.cookie属性来设置cookie
  document.cookie = cookie;
 };
 // 删除指定的cookie
 this.removeItem = function(key) {
  if (!(key in cookies)) return;
  // 如果cookie不存在,则什么也不做
  // 从内部维护的cookies组删除指定的cookie
  delete cookies[key];
  // 同时将cookie中的名字也在内部的数组中删除.
  // 如果使用ES5定义的数组indexOf()方法会更加简单.
  for(var i = 0; i < keys.length; i++) {
  // 遍历所有的名字
   if (keys[i] === key) { 
   // 当我们找到了要找的那个
    keys.splice(i,1); 
 // 将它从数组中删除.
    break;
   }
  }
  this.length--; 
  // cookies个数减一
  // 最终通过将该cookie的值设置为空字符串
  //以及将有效期设置为0来删除指定的cookie.
  document.cookie = key + "=; max-age=0";
 };
 // 删除所有的cookies
 this.clear = function() {
  // 循环所有的cookies的名字,并将cookies删除
  for(var i = 0; i < keys.length; i++)
   document.cookie = keys[i] + "=; max-age=0";
  // 重置所有的内部状态
  cookies = {};
  keys = [];
  this.length = 0;
 };
}

I hope this article will be helpful to everyone’s JavaScript programming design.

Statement
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
Understanding the JavaScript Engine: Implementation DetailsUnderstanding the JavaScript Engine: Implementation DetailsApr 17, 2025 am 12:05 AM

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python vs. JavaScript: The Learning Curve and Ease of UsePython vs. JavaScript: The Learning Curve and Ease of UseApr 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.

Python vs. JavaScript: Community, Libraries, and ResourcesPython vs. JavaScript: Community, Libraries, and ResourcesApr 15, 2025 am 12:16 AM

Python and JavaScript have their own advantages and disadvantages in terms of community, libraries and resources. 1) The Python community is friendly and suitable for beginners, but the front-end development resources are not as rich as JavaScript. 2) Python is powerful in data science and machine learning libraries, while JavaScript is better in front-end development libraries and frameworks. 3) Both have rich learning resources, but Python is suitable for starting with official documents, while JavaScript is better with MDNWebDocs. The choice should be based on project needs and personal interests.

From C/C   to JavaScript: How It All WorksFrom C/C to JavaScript: How It All WorksApr 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.

JavaScript Engines: Comparing ImplementationsJavaScript Engines: Comparing ImplementationsApr 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.

Beyond the Browser: JavaScript in the Real WorldBeyond the Browser: JavaScript in the Real WorldApr 12, 2025 am 12:06 AM

JavaScript's applications in the real world include server-side programming, mobile application development and Internet of Things control: 1. Server-side programming is realized through Node.js, suitable for high concurrent request processing. 2. Mobile application development is carried out through ReactNative and supports cross-platform deployment. 3. Used for IoT device control through Johnny-Five library, suitable for hardware interaction.

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

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

See all articles

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

AI Hentai Generator

AI Hentai Generator

Generate AI Hentai for free.

Hot Article

R.E.P.O. Energy Crystals Explained and What They Do (Yellow Crystal)
1 months agoBy尊渡假赌尊渡假赌尊渡假赌
R.E.P.O. Best Graphic Settings
1 months agoBy尊渡假赌尊渡假赌尊渡假赌
R.E.P.O. How to Fix Audio if You Can't Hear Anyone
1 months agoBy尊渡假赌尊渡假赌尊渡假赌
R.E.P.O. Chat Commands and How to Use Them
1 months agoBy尊渡假赌尊渡假赌尊渡假赌

Hot Tools

EditPlus Chinese cracked version

EditPlus Chinese cracked version

Small size, syntax highlighting, does not support code prompt function

WebStorm Mac version

WebStorm Mac version

Useful JavaScript development tools

Safe Exam Browser

Safe Exam Browser

Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

SublimeText3 English version

SublimeText3 English version

Recommended: Win version, supports code prompts!

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment