search
HomeWeb Front-endFront-end Q&AHow to write post submission in javascript

In front-end development, we often need to use AJAX technology to send HTTP requests, including POST requests. This article will explain how to write a POST request in JavaScript.

1. Basic concepts of POST requests

First of all, we need to understand the basic concepts of POST requests.

In the HTTP protocol, GET and POST are both commonly used request methods. The main difference is:

  1. The GET request puts the parameters directly in the URL and passes them, while the POST request Parameters are placed in the request body.
  2. The amount of data transmitted by the GET request is small, generally no more than 1KB, while the POST request has no limit and can transmit a large amount of data.
  3. GET requests are unsafe because the parameters in the URL can be viewed or modified by the user, while POST requests are relatively safe because the parameters are placed in the request body.

The above is the basic concept of POST request. Next, we will introduce how to write POST request in JavaScript.

2. Use the XMLHttpRequest object to send POST requests

In JavaScript, we can use the XMLHttpRequest object to send HTTP requests, including GET and POST requests.

The XMLHttpRequest object is a JavaScript API that can be used to exchange data with the server in the background. It can load data asynchronously through AJAX technology and be able to update the page without reloading the entire page.

The following are the basic steps to use the XMLHttpRequest object to send a POST request:

  1. Create an XMLHttpRequest object

First, we need to create an XMLHttpRequest object. This can be achieved using the following code:

var xhr = new XMLHttpRequest();
  1. Set the path and parameters of the request

Next, we need to set the path and parameters of the request. These parameters will be placed in the request body. This can be achieved using the following code:

xhr.open('POST', 'http://example.com/api', true);
xhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
xhr.send('name=John&age=25');

In the above code, we set the request path to http://example.com/api, and the parameters are name=John and age=25.

In addition, the request header Content-type is also set to application/x-www-form-urlencoded. This is a standard POST request header, telling the server that the parameters in the request body are in key-value format.

  1. Receive the data returned by the server

Finally, we need to receive the data returned by the server. This can be achieved using the following code:

xhr.onreadystatechange = function() {
  if(xhr.readyState == XMLHttpRequest.DONE && xhr.status == 200) {
    console.log(xhr.responseText);
  }
}

In the above code, we set the onreadystatechange event handler of XMLHttpRequest. When readyState becomes 4 (that is, the request is completed) and the status code is 200, it means that the server has responded successfully and returned the data. At this time, the data returned by the server can be obtained through xhr.responseText.

3. Use the fetch API to send a POST request

In addition to the XMLHttpRequest object, you can also use the fetch API to send a POST request. The fetch API is a standard JavaScript API for sending HTTP requests between the client and the server and encapsulating the server response using a Promise object.

The following are the basic steps to send a POST request using the fetch API:

  1. Set the path and parameters of the request

First, we need to set the path of the request and parameters. This can be achieved using the following code:

fetch('http://example.com/api', {
  method: 'POST',
  headers: {
    'Content-type': 'application/x-www-form-urlencoded'
  },
  body: 'name=John&age=25'
})
.then(response => response.json())
.then(data => console.log(data))
.catch(error => console.error(error));

In the above code, we set the request path to http://example.com/api, and the parameters are name=John and age=25.

In addition, the request header Content-type is also set to application/x-www-form-urlencoded. This is a standard POST request header, telling the server that the parameters in the request body are in key-value format.

  1. Receive the data returned by the server

Finally, we need to receive the data returned by the server. You can use the Promise object of the fetch API to handle it. This can be achieved using the following code:

.then(response => response.json())
.then(data => console.log(data))
.catch(error => console.error(error));

In the above code, we use the response.json() method to convert the response body into JSON format, and process the response data through the then() method, and through the catch() method Handle exceptions.

4. Summary

Through the methods introduced in this article, we can write POST requests in JavaScript, including using the XMLHttpRequest object and fetch API. These methods can load data asynchronously and update the page without reloading the entire page. You can choose the appropriate method to send POST requests based on actual needs.

The above is the detailed content of How to write post submission in javascript. For more information, please follow other related articles on the PHP Chinese website!

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
React's SEO-Friendly Nature: Improving Search Engine VisibilityReact's SEO-Friendly Nature: Improving Search Engine VisibilityApr 26, 2025 am 12:27 AM

Yes,ReactapplicationscanbeSEO-friendlywithproperstrategies.1)Useserver-siderendering(SSR)withtoolslikeNext.jstogeneratefullHTMLforindexing.2)Implementstaticsitegeneration(SSG)forcontent-heavysitestopre-renderpagesatbuildtime.3)Ensureuniquetitlesandme

React's Performance Bottlenecks: Identifying and Optimizing Slow ComponentsReact's Performance Bottlenecks: Identifying and Optimizing Slow ComponentsApr 26, 2025 am 12:25 AM

React performance bottlenecks are mainly caused by inefficient rendering, unnecessary re-rendering and calculation of component internal heavy weight. 1) Use ReactDevTools to locate slow components and apply React.memo optimization. 2) Optimize useEffect to ensure that it only runs when necessary. 3) Use useMemo and useCallback for memory processing. 4) Split the large component into small components. 5) For big data lists, use virtual scrolling technology to optimize rendering. Through these methods, the performance of React applications can be significantly improved.

Alternatives to React: Exploring Other JavaScript UI Libraries and FrameworksAlternatives to React: Exploring Other JavaScript UI Libraries and FrameworksApr 26, 2025 am 12:24 AM

Someone might look for alternatives to React because of performance issues, learning curves, or exploring different UI development methods. 1) Vue.js is praised for its ease of integration and mild learning curve, suitable for small and large applications. 2) Angular is developed by Google and is suitable for large applications, with a powerful type system and dependency injection. 3) Svelte provides excellent performance and simplicity by compiling it into efficient JavaScript at build time, but its ecosystem is still growing. When choosing alternatives, they should be determined based on project needs, team experience and project size.

Keys and React's Reconciliation Algorithm: Improving PerformanceKeys and React's Reconciliation Algorithm: Improving PerformanceApr 26, 2025 am 12:21 AM

KeysinReactarespecialattributesassignedtoelementsinarraysforstableidentity,crucialforthereconciliationalgorithmwhichupdatestheDOMefficiently.1)KeyshelpReacttrackchanges,additions,orremovalsinlists.2)Usingunique,stablekeyslikeIDsratherthanindicespreve

The Boilerplate Code Required for React Projects: Reducing Setup OverheadThe Boilerplate Code Required for React Projects: Reducing Setup OverheadApr 26, 2025 am 12:19 AM

ToreducesetupoverheadinReactprojects,usetoolslikeCreateReactApp(CRA),Next.js,Gatsby,orstarterkits,andmaintainamodularstructure.1)CRAsimplifiessetupwithasinglecommand.2)Next.jsandGatsbyoffermorefeaturesbutalearningcurve.3)Starterkitsprovidecomprehensi

Understanding useState(): A Comprehensive Guide to React State ManagementUnderstanding useState(): A Comprehensive Guide to React State ManagementApr 25, 2025 am 12:21 AM

useState()isaReacthookusedtomanagestateinfunctionalcomponents.1)Itinitializesandupdatesstate,2)shouldbecalledatthetoplevelofcomponents,3)canleadto'stalestate'ifnotusedcorrectly,and4)performancecanbeoptimizedusinguseCallbackandproperstateupdates.

What are the advantages of using React?What are the advantages of using React?Apr 25, 2025 am 12:16 AM

Reactispopularduetoitscomponent-basedarchitecture,VirtualDOM,richecosystem,anddeclarativenature.1)Component-basedarchitectureallowsforreusableUIpieces,improvingmodularityandmaintainability.2)TheVirtualDOMenhancesperformancebyefficientlyupdatingtheUI.

Debugging in React: Identifying and Resolving Common IssuesDebugging in React: Identifying and Resolving Common IssuesApr 25, 2025 am 12:09 AM

TodebugReactapplicationseffectively,usethesestrategies:1)AddresspropdrillingwithContextAPIorRedux.2)HandleasynchronousoperationswithuseStateanduseEffect,usingAbortControllertopreventraceconditions.3)OptimizeperformancewithuseMemoanduseCallbacktoavoid

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

VSCode Windows 64-bit Download

VSCode Windows 64-bit Download

A free and powerful IDE editor launched by Microsoft

DVWA

DVWA

Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

Atom editor mac version download

Atom editor mac version download

The most popular open source editor

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

mPDF

mPDF

mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),