nodejs installation and verification code

1. Installation of Node.js

Node.js is a Javascript running environment based on the V8 engine. It can run Javascript code on the server side. It is one of the most popular web development languages ​​at present. This article will introduce how to install Node.js on Windows systems.

1. Download the installation package

First, we need to download the corresponding version of the installation package from the Node.js official website. You can choose to download the corresponding installation package according to your own system version, which is generally divided into 32-bit and 64-bit.

2. Install Node.js

After downloading, double-click the installation package to start the installation. During the installation process, you need to pay attention to selecting the appropriate installation path and related components, such as whether to install npm (Node Package Manager), etc.

After the installation is completed, you can open the command line tool (such as Windows cmd or PowerShell) and enter the following command to confirm:

node -v

If the version number of Node.js is output, it means installation success.

2. Verification code generation and verification

Verification code is a common identity verification mechanism and is widely used in web development. This article will introduce how to use Node.js to generate and verify verification codes.

1. Installing dependencies

First, we need to install a package of Node.js - svg-captcha. This package can generate verification code images in SVG format and provide verification functions. It can be installed through npm:

npm install svg-captcha --save

After the installation is completed, the svg-captcha package can be found in the node_modules directory of the project.

2. Generate verification code

To generate verification code, you need to call the create method provided by the svg-captcha package and pass in the options parameter:

const svgCaptcha = require('svg-captcha');

const captcha = svgCaptcha.create({
    size: 4, // 验证码长度
    ignoreChars: '0o1i', // 验证码字符中排除的字母
    noise: 2, // 干扰线条的数量
    color: true // 验证码的字符是否有颜色，默认是黑色的
});

console.log(captcha.text); // 验证码的值
console.log(captcha.data); // 验证码的SVG图片

This code snippet A random 4-digit verification code will be generated and the verification code value and SVG image data will be returned. SVG images can be output directly to the front end for display when users enter the verification code.

3. Verification verification code

After the user enters the verification code, verification is required. During verification, the verification code value entered by the user needs to be compared with the generated verification code value. If they are consistent, the verification is passed.

app.post('/login', function(req, res) {
    const code = req.body.code; // 获取用户输入的验证码
    const sessionCode = req.session.captcha; // 获取生成的验证码

    if (code.toLowerCase() === sessionCode.toLowerCase()) {
        // 验证成功
    } else {
        // 验证失败
    }
});

Since the verification code is not case-sensitive, both need to be converted to lowercase letters during comparison. At the same time, the generated verification code value needs to be stored in the session so that it can be obtained during verification. In the express framework, session operations can be performed through req.session.

In short, Node.js can generate and verify verification codes very conveniently, providing a reliable authentication method for web development.

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