js限制特殊字符

function validateUsername(username) {
    const regex = /^[a-zA-Z0-9]+$/;
    return regex.test(username);
}

document.getElementById('username').addEventListener('input', function (e) {
    if (!validateUsername(e.target.value)) {
        e.target.setCustomValidity('用户名只能包含字母和数字');
    } else {
        e.target.setCustomValidity('');
    }
});

const express = require('express');
const app = express();

app.use(express.json());

app.post('/register', (req, res) => {
    const { username } = req.body;
    const regex = /^[a-zA-Z0-9]+$/;
    if (!regex.test(username)) {
        return res.status(400).send('用户名只能包含字母和数字');
    }
    // 继续处理注册逻辑
    res.send('注册成功');
});

app.listen(3000, () => {
    console.log('服务器运行在 http://localhost:3000');
});