search
HomeWeb Front-endJS TutorialExample of jQuery+koa2 implementing a simple Ajax request

This article mainly introduces examples of jQuery koa2 implementing simple Ajax requests. Now I share it with you and give it as a reference.

Preface

Before writing Ajax code, I only focused on the front-end implementation. I felt that this led to my insufficient understanding of Ajax requests, so I wrote this from front-end to back-end. Ajax implements a small demo, implementing simple GET and POST requests respectively, to deepen the understanding of front-end and back-end interaction.

Technology stack

  1. koa2

  2. jQuer

Requirements

Some logic can be processed directly on the front end. It is sent to the backend for processing here to better understand the Ajax request.

POST

Save personnel information by filling in the number and name and sending a POST request. When the information is not filled in or is filled in incorrectly, a format error reminder is given; when When the information is filled in correctly but the number already exists, a reminder that the number already exists is given; when the information is filled in correctly and the number does not exist, it displays successful saving.

GET

Query personnel information by filling in the number and sending a GET request. When the number is not filled in or is filled incorrectly, a format error reminder is given; when the number is filled in If the information is correct and the number already exists, the person information will be returned; if the information is filled in correctly but the number does not exist, an error reminder that the person does not exist will be displayed.

File list

  1. dist

    1. ##index.html

    2. index.js

  2. server.js

  3. router.js

Front-end implementation

html page

##index.html

, a simple html page, by clicking Button sends Ajax request in json format:

<!DOCTYPE html>
<html>
<head>
 <meta charset="UTF-8">
 <title>Document</title>
 <script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.js"></script>
</head>
<body>
 <p>
 <h1 id="Hello-nbsp-World">Hello World</h1>
 <label for="person-number">编号</label>
 <input type="text" id="person-number">
 <label for="person-name">姓名</label>
 <input type="text" id="person-name">
 <button id="save">保存信息</button>
 <label for="search-number">编号</label>
 <input type="text" id="search-number">
 <button id="search">查询信息</button>
 <br>
 <br>
 <p id="message"></p>
 </p>
 <!-- jQuery实现代码 -->
 <script src="./index.js"><script>
</body>
</html>

jQuery sends Ajax request

Send

GET

request:

var searchButton = $(&#39;#search&#39;);
var personNumber = $(&#39;#person-number&#39;).val();
searchButton.click(() => {
 var number = $(&#39;#search-number&#39;).val();
 $.ajax({
 type: &#39;GET&#39;,
 url: `person/?number=${number}`
 })
});

Send

POST

request:

var saveButton = $(&#39;#save&#39;).click(() => {
 var number = $(&#39;#person-number&#39;).val();
 var name = $(&#39;#person-name&#39;).val();
 $.ajax({
 type: &#39;POST&#39;,
 url: &#39;person&#39;,
 dataType: &#39;json&#39;,
 data: {
  number: number,
  name: name
 }
 })
});

Process the returned json data

Process the returned data through the

ajaxComplete

event, this event can only be bound To the document object:

// Ajax完成事件
$(document).ajaxComplete(function(event, xhr, settings) {
 var obj = JSON.parse(xhr.responseText);
 var data = obj.data;
 if(obj.success && data[&#39;number&#39;]){
 $(&#39;#message&#39;).text(`姓名:${data[&#39;name&#39;]} 编号:${data[&#39;number&#39;]}`);
 } else {
 $(&#39;#message&#39;).text(data);
 }
});

Backend implementation

web server

Implement a simple web server through

koa2

. server.js:

const path = require(&#39;path&#39;);
const serve = require(&#39;koa-static&#39;);
const Koa = require(&#39;koa&#39;);
const koaBody = require(&#39;koa-body&#39;); // 解析 multipart、urlencoded和json格式的请求体
const router = require(&#39;./router.js&#39;);

const app = new Koa();

app.use(serve(path.join(__dirname, &#39;./dist&#39;))); // 读取前端静态页面
app.use(koaBody()); // 通过该中间件解析POST请求的请求体才能拿到数据
app.use(router.routes());
app.listen(3000);

console.log(&#39;listening on port 3000&#39;);

Handling requests via routing

Handling

GET

Request and return data in the form of json string. Query parameters sent through the GET request will be stored in the ctx.query attribute in the form of object literals:

router.get(&#39;/person&#39;, (ctx, next) => {
 let number = ctx.query.number;
 let temp = {};
 // 判断编号是否存在
 temp.data = /^[0-9]+$/.test(number) ? (people[number] ? people[number] : &#39;编号不存在&#39; ) : &#39;编号格式错误&#39;;
 temp.success = !!temp.data[&#39;number&#39;];
 ctx.body = JSON.stringify(temp); // 响应请求,发送处理后的信息给客户端
});

Handle

POST

requests and return data in the form of json strings. The data of the POST request is stored in the request body of the request. It needs to be automatically parsed by the koa-body middleware before the requested data can be obtained through ctx.request.body:

router.post(&#39;/person&#39;, (ctx, next) => {
 let query = ctx.request.body;
 let temp = {};
 // 编号必须是数字并且大于0,名字必须存在
 if (/^[0-9]+$/.test(query.number) && query.name && parseInt(query.number, 10) > 0) {
 // 判断编号是否存在
 if (!people[query.number]) {
  // 保存信息
  people[query.number] = {
  number: parseInt(query.number, 10),
  name: query.name
  };
  temp.success = true;
  temp.data = &#39;保存成功&#39;;
 } else {
  temp.success = false;
  temp.data = &#39;编号已存在&#39;;
 }
 } else {
 temp.success = false;
 temp.data = &#39;信息格式错误&#39;;
 }
 ctx.body = JSON.stringify(temp);
});

Complete

router.js

:

const Router = require('koa-router');

const router = new Router();

// 初始的人员信息对象,信息从这里储存和读取。
const people = {
 1: { number: 1, name: 'Dan Friedell' },
 2: { number: 2, name: 'Anna Matteo' },
 3: { number: 3, name: 'Susan Shand' },
 4: { number: 4, name: 'Bryan Lynn' },
 5: { number: 5, name: 'Mario Ritter' },
};

router.get('/person', (ctx, next) => {
 let number = ctx.query.number;
 let temp = {}; // 要返回给客户端的对象,通过success属性判断存取是否成功。
 // 判断编号是否存在
 temp.data = /^[0-9]+$/.test(number) ? (people[number] ? people[number] : '编号不存在' ) : '编号格式错误';
 temp.success = !!temp.data['number'];
 ctx.body = JSON.stringify(temp);
});

router.post(&#39;/person&#39;, (ctx, next) => {
 let query = ctx.request.body;
 let temp = {};
 // 编号必须是数字并且大于0,名字必须存在
 if (/^[0-9]+$/.test(query.number) && query.name && parseInt(query.number, 10) > 0) {
 // 判断编号是否存在
 if (!people[query.number]) {
  // 保存信息
  people[query.number] = {
  number: parseInt(query.number, 10),
  name: query.name
  };
  temp.success = true;
  temp.data = &#39;保存成功&#39;;
 } else {
  temp.success = false;
  temp.data = &#39;编号已存在&#39;;
 }
 } else {
 temp.success = false;
 temp.data = &#39;信息格式错误&#39;;
 }
 ctx.body = JSON.stringify(temp);
});


module.exports = router;

Test

Enter

node server.js

in the console and you can see that the server is running on port 3000. Open the browser and enter localhost:3000 and you can see it. A simple front-end page:

Query data:

Save data :

Query the data again:

The above is what I compiled for everyone. I hope it will be helpful to everyone in the future. .

Related articles:

Sample code of actual node static file server


vue.js or js implements Chinese A-Z sorting The method


vue.js moves the array position and updates the view at the same time


The above is the detailed content of Example of jQuery+koa2 implementing a simple Ajax request. 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
The Future of Python and JavaScript: Trends and PredictionsThe Future of Python and JavaScript: Trends and PredictionsApr 27, 2025 am 12:21 AM

The future trends of Python and JavaScript include: 1. Python will consolidate its position in the fields of scientific computing and AI, 2. JavaScript will promote the development of web technology, 3. Cross-platform development will become a hot topic, and 4. Performance optimization will be the focus. Both will continue to expand application scenarios in their respective fields and make more breakthroughs in performance.

Python vs. JavaScript: Development Environments and ToolsPython vs. JavaScript: Development Environments and ToolsApr 26, 2025 am 12:09 AM

Both Python and JavaScript's choices in development environments are important. 1) Python's development environment includes PyCharm, JupyterNotebook and Anaconda, which are suitable for data science and rapid prototyping. 2) The development environment of JavaScript includes Node.js, VSCode and Webpack, which are suitable for front-end and back-end development. Choosing the right tools according to project needs can improve development efficiency and project success rate.

Is JavaScript Written in C? Examining the EvidenceIs JavaScript Written in C? Examining the EvidenceApr 25, 2025 am 12:15 AM

Yes, the engine core of JavaScript is written in C. 1) The C language provides efficient performance and underlying control, which is suitable for the development of JavaScript engine. 2) Taking the V8 engine as an example, its core is written in C, combining the efficiency and object-oriented characteristics of C. 3) The working principle of the JavaScript engine includes parsing, compiling and execution, and the C language plays a key role in these processes.

JavaScript's Role: Making the Web Interactive and DynamicJavaScript's Role: Making the Web Interactive and DynamicApr 24, 2025 am 12:12 AM

JavaScript is at the heart of modern websites because it enhances the interactivity and dynamicity of web pages. 1) It allows to change content without refreshing the page, 2) manipulate web pages through DOMAPI, 3) support complex interactive effects such as animation and drag-and-drop, 4) optimize performance and best practices to improve user experience.

C   and JavaScript: The Connection ExplainedC and JavaScript: The Connection ExplainedApr 23, 2025 am 12:07 AM

C and JavaScript achieve interoperability through WebAssembly. 1) C code is compiled into WebAssembly module and introduced into JavaScript environment to enhance computing power. 2) In game development, C handles physics engines and graphics rendering, and JavaScript is responsible for game logic and user interface.

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.

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

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),

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

VSCode Windows 64-bit Download

VSCode Windows 64-bit Download

A free and powerful IDE editor launched by Microsoft

Atom editor mac version download

Atom editor mac version download

The most popular open source editor

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.