Node.js is a very popular server-side JavaScript runtime environment. It has the advantages of being lightweight, efficient, and easy to expand. It is widely used in web applications, command line tools, Internet of Things and other fields, but in some cases In some cases, it will still encounter some problems, such as garbled characters. In this article, we will explore the causes and solutions to Node.js garbled issues.
1. Reasons for the garbled code problem
In Node.js, JavaScript strings use UTF-8 encoding by default. But in some cases, such as reading files, requesting the network and other operations, the returned string is not necessarily UTF-8 encoded. If the program does not handle this situation correctly, garbled characters may easily occur.
For example, when we read a GBK-encoded text file, if we do not specify the encoding format, it is easy to encounter garbled code problems:
const fs = require('fs');
fs.readFile('file.txt', (err, data) => {
if (err) throw err;
console.log(data.toString()); // 输出乱码
})The solution is to read the file, Specify the correct encoding format, such as:
const fs = require('fs');
fs.readFile('file.txt', { encoding: 'GBK' }, (err, data) => {
if (err) throw err;
console.log(data.toString()); // 输出正确的文本
})In the Node.js server, when the client initiates a request and gets the response, The response header needs to specify the character encoding of the response content. If the character set is not specified in the response header, or the specified character set is inconsistent with the actual character set used, garbled characters will occur.
For example, we use the Express framework to create an HTTP server. If the returned HTML text does not specify the encoding, it is easy to encounter garbled problems:
const express = require('express');
const app = express();
app.get('/', (req, res) => {
res.send('<html><body>中文</body></html>'); // 输出乱码
});
app.listen(8080, () => {
console.log('Server started on http://localhost:8080/');
});The solution is to specify it clearly in the response header The character set of the response content, for example:
const express = require('express');
const app = express();
app.get('/', (req, res) => {
res.set('Content-Type', 'text/html; charset=utf8');
res.send('<html><body>中文</body></html>'); // 输出正确的文本
});
app.listen(8080, () => {
console.log('Server started on http://localhost:8080/');
});In Node.js, when interacting with the database, sometimes the database encoding and Node.js will appear Inconsistent character encodings. For example, in the MySQL database, the commonly used character encodings are latin1 and utf8, while the default encoding of Node.js is utf8. If we do not specify the encoding when querying, garbled characters may occur.
For example, we use the mysql module to query the MySQL database. If the encoding is not specified, it is easy to encounter garbled code problems:
const mysql = require('mysql');
const connection = mysql.createConnection({
host: 'localhost',
user: 'root',
password: 'password',
database: 'test'
});
connection.connect();
connection.query('SELECT * FROM users', (error, results, fields) => {
if (error) throw error;
console.log(results); // 输出乱码
});
connection.end();The solution is to specify the correct encoding format when querying, such as ：
const mysql = require('mysql');
const connection = mysql.createConnection({
host: 'localhost',
user: 'root',
password: 'password',
database: 'test'
});
connection.connect();
connection.query('SELECT * FROM users', { charset: 'GBK' }, (error, results, fields) => {
if (error) throw error;
console.log(results); // 输出正确的文本
});
connection.end();2. Solution to the garbled code problem
In Node.js, you can use the Buffer class to process binary data. Includes character set conversion. Use the Buffer.from() method to convert a string into binary data with a specified encoding, and use the buf.toString() method to convert binary data into a string with a specified encoding.
For example, when we read a GBK-encoded text file, we can use the Buffer class to deal with the garbled problem:
const fs = require('fs');
fs.readFile('file.txt', (err, data) => {
if (err) throw err;
const buf = Buffer.from(data, 'binary');
console.log(buf.toString('GBK')); // 输出正确的文本
})In Node.js, many APIs provide parameters for specifying character encoding, such as { encoding: 'GBK' } when reading files, charset=utf8 in the response header, and { charset: 'GBK' } when querying the database. wait. Correct use of these parameters can avoid garbled characters.
For example, when we use the Express framework to create an HTTP server, we can specify the encoding in the response header:
const express = require('express');
const app = express();
app.get('/', (req, res) => {
res.set('Content-Type', 'text/html; charset=utf8');
res.send('<html><body>中文</body></html>');
});
app.listen(8080, () => {
console.log('Server started on http://localhost:8080/');
});In the Node.js server, unifying character encoding can also avoid garbled characters. We can set the encoding format of all strings to UTF-8, which can avoid garbled characters caused by inconsistent encoding.
For example, we can use the iconv-lite module to implement encoding conversion:
const iconv = require('iconv-lite');
const buffer = iconv.encode('中文', 'GBK');
console.log(buffer); // <Buffer d6 d0 ce c4>
const str = iconv.decode(buffer, 'GBK');
console.log(str); // 中文In short, it is very common to encounter garbled code problems in Node.js, but as long as the source of the problem is correctly identified , these problems can be easily solved by adopting corresponding solutions.
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