search
HomeWeb Front-endJS TutorialDetailed explanation of JavaScript cookie technology

Use JS to set cookies, read cookies, and delete cookies
JavaScript is a script that runs on the client side, so it is generally not possible to set up a Session because the Session runs on the server side.

And cookies run on the client, so you can use JS to set cookies.

Suppose there is such a situation, in a certain use case process, jump from page A to page B, if JS is used in page A The variable temp is used to save the value of a certain variable. When you are on page B, you also need to use JS to reference the variable value of temp. The life cycle of global variables or static variables in JS is limited. When a page jump occurs or When the page is closed, the values ​​of these variables will be reloaded, that is, the saved effect will not be achieved. The best solution to this problem is to use cookies to save the value of the variable. So how to set and read cookies?
First of all, you need to understand the structure of cookies a little bit. Simply put: cookies are saved in the form of key-value pairs, that is, in the key=value format. Each cookie is usually separated by ";".

JS setting cookie:

Assume that in page A, you want to save the value of the variable username ("jack") to the cookie, and the key value is name, then the corresponding JS code is:
document.cookie="name="+ username;

JS reads cookie:
Assume that the content stored in the cookie is: name=jack; password=123

Then the JS code to get the value of the variable username in page B is as follows:

var username=document.cookie.split(";")[0].split("=")[1];
 
//JS操作cookies方法!
 
//写cookies
 
function setCookie(name,value)
{
  var Days = 30;
  var exp = new Date();
  exp.setTime(exp.getTime() + Days*24*60*60*1000);
  document.cookie = name + "="+ escape (value) + ";expires=" + exp.toGMTString();
}
 
//读取cookies
function getCookie(name)
{
  var arr,reg=new RegExp("(^| )"+name+"=([^;]*)(;|$)");
 
  if(arr=document.cookie.match(reg))
 
    return unescape(arr[2]);
  else
    return null;
}
 
//删除cookies
function delCookie(name)
{
  var exp = new Date();
  exp.setTime(exp.getTime() - 1);
  var cval=getCookie(name);
  if(cval!=null)
    document.cookie= name + "="+cval+";expires="+exp.toGMTString();
}
//使用示例
setCookie("name","hayden");
alert(getCookie("name"));
 
//如果需要设定自定义过期时间
//那么把上面的setCookie 函数换成下面两个函数就ok;
 
 
//程序代码
function setCookie(name,value,time)
{
  var strsec = getsec(time);
  var exp = new Date();
  exp.setTime(exp.getTime() + strsec*1);
  document.cookie = name + "="+ escape (value) + ";expires=" + exp.toGMTString();
}
function getsec(str)
{
  alert(str);
  var str1=str.substring(1,str.length)*1;
  var str2=str.substring(0,1);
  if (str2=="s")
  {
    return str1*1000;
  }
  else if (str2=="h")
  {
    return str1*60*60*1000;
  }
  else if (str2=="d")
  {
    return str1*24*60*60*1000;
  }
}

//这是有设定过期时间的使用示例:
//s20是代表20秒
//h是指小时,如12小时则是:h12
//d是天数,30天则:d30
 
setCookie(“name”,”hayden”,”s20”);


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
From Websites to Apps: The Diverse Applications of JavaScriptFrom Websites to Apps: The Diverse Applications of JavaScriptApr 22, 2025 am 12:02 AM

JavaScript is widely used in websites, mobile applications, desktop applications and server-side programming. 1) In website development, JavaScript operates DOM together with HTML and CSS to achieve dynamic effects and supports frameworks such as jQuery and React. 2) Through ReactNative and Ionic, JavaScript is used to develop cross-platform mobile applications. 3) The Electron framework enables JavaScript to build desktop applications. 4) Node.js allows JavaScript to run on the server side and supports high concurrent requests.

Python vs. JavaScript: Use Cases and Applications ComparedPython vs. JavaScript: Use Cases and Applications ComparedApr 21, 2025 am 12:01 AM

Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.

The Role of C/C   in JavaScript Interpreters and CompilersThe Role of C/C in JavaScript Interpreters and CompilersApr 20, 2025 am 12:01 AM

C and C play a vital role in the JavaScript engine, mainly used to implement interpreters and JIT compilers. 1) C is used to parse JavaScript source code and generate an abstract syntax tree. 2) C is responsible for generating and executing bytecode. 3) C implements the JIT compiler, optimizes and compiles hot-spot code at runtime, and significantly improves the execution efficiency of JavaScript.

JavaScript in Action: Real-World Examples and ProjectsJavaScript in Action: Real-World Examples and ProjectsApr 19, 2025 am 12:13 AM

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

JavaScript and the Web: Core Functionality and Use CasesJavaScript and the Web: Core Functionality and Use CasesApr 18, 2025 am 12:19 AM

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

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.

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

Video Face Swap

Video Face Swap

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

Hot Tools

MantisBT

MantisBT

Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

Dreamweaver Mac version

Dreamweaver Mac version

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

PhpStorm Mac version

PhpStorm Mac version

The latest (2018.2.1) professional PHP integrated development tool

WebStorm Mac version

WebStorm Mac version

Useful JavaScript development tools