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nodejs character ratio then

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2023-05-17 09:05:07488browse

Title: Node.js character encoding is so important, do you understand it?

Node.js is a popular server-side JavaScript runtime environment that uses the V8 engine to interpret JavaScript code and provides many core and third-party modules for building efficient network applications. Character encoding is a very important topic when developing with Node.js, especially when dealing with input and output. This article will introduce the basic knowledge and related issues of Node.js character encoding to help readers better understand and handle character encoding.

1. Basic concepts of character encoding

Character encoding is an algorithm for converting characters and numbers. It can represent character data as digital data or binary data, thereby facilitating computer processing and transmission. Common character encodings include ASCII, Unicode, UTF-8, etc.

ASCII encoding only uses 7-bit binary, with a total of 128 characters, including basic English letters, numbers, special symbols, control characters, etc. In order to solve the problem of multi-language character sets, Unicode encoding has introduced more encoding schemes, including UTF-8, UTF-16 and UTF-32. UTF-8 is a variable-length encoding scheme that can use 1 to 4 bytes to represent a character. It is compatible with ASCII encoding and supports text worldwide.

In Node.js, strings are stored in UTF-8 encoding. By default, strings read or output are also encoded and decoded in UTF-8 format. However, sometimes we need to use other encoding schemes to handle input or output, such as ASCII, GB2312, GBK, ISO-8859-1, Shift_JIS, etc. At this time, we need to use some encoding encapsulation methods provided by Node.js to encode and decode.

2. Issues related to Node.js character encoding

In Node.js, character encoding mainly involves two aspects: input and output. Let’s discuss them separately below:

  1. Input problem

In Node.js, we usually use the fs module to read file or network I/O data, and the character encoding of these data may be uncertain or different based on the default encoding. In this case, we need to use third-party modules such as iconv-lite or node-iconv to decode into UTF-8 encoding for subsequent processing.

iconv-lite is a popular character encoding conversion tool that is compatible with the Buffer type in Node.js. By using iconv-lite, we can convert strings of different encodings into UTF-8 encoding to facilitate subsequent data processing: 

const iconv = require('iconv-lite');
const fs = require('fs');

const buffer = fs.readFileSync('test.txt');
const str = iconv.decode(buffer, 'GB2312');
console.log(str);

node-iconv is another more native character encoding conversion module. More efficient low-level character encoding conversion can be achieved without involving intermediate character set encoding conversion. Code example here: 

const iconv = require('iconv-lite');
const fs = require('fs');
const Iconv = require('node-iconv').Iconv;

const converter = new Iconv('UTF-8', 'GB2312');
const buffer = fs.readFileSync('test.txt');
const str = iconv.decode(converter.convert(buffer), 'GB2312');
console.log(str);
  1. Output problem

In Node.js, when outputting data, we also need to specify the encoding method of the output character set to ensure output The character set is consistent with the character set we want.

For example, when using an HTTP server or Express framework, we can use the res.set() or res.setHeader() method to set the content type and character encoding of the response header: 

const http = require('http');

const server = http.createServer((req, res) => {
    res.setHeader('Content-Type', 'text/html; charset=utf-8');
    res.end('Hello 世界');
});

server.listen(3000);

In addition When using the Node.js template engine, you also need to pay special attention to character encoding issues. For example, when using the EJS template engine, we can specify the output character set encoding through - charset specification: 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title><%= title %></title>
</head>
<body>
    <h1><%= message %></h1>
</body>
</html>

If it is incorrect If the character encoding is set incorrectly, garbled, unrecognizable, � and other characters will appear, which will affect the effect and use of the application.

3. Summary

Character encoding is a very important knowledge point in Node.js. When dealing with character encoding, we need to pay attention to the following points:

  1. UTF-8 encoding is used by default, but be aware that input and output may use other encoding methods.
  2. Different encodings need to be converted when inputting, such as iconv-lite or node-iconv and other modules.
  3. The correct character encoding must be set when outputting, such as res.setHeader(), template engine, etc.

Only by correctly understanding and using character encoding related knowledge can we better develop efficient Node.js applications.

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