js实现参数化

// 非参数化函数
function greet() {
    console.log("Hello, World!");
}

// 参数化函数
function greet(name) {
    console.log(`Hello, ${name}!`);
}

greet("Alice"); // 输出: Hello, Alice!

const mysql = require('mysql');
const connection = mysql.createConnection({
    host: 'localhost',
    user: 'user',
    password: 'password',
    database: 'mydb'
});

connection.connect();

const userId = 1;
const query = 'SELECT * FROM users WHERE id = ?';
connection.query(query, [userId], (error, results, fields) => {
    if (error) throw error;
    console.log(results);
});

connection.end();

// config.js
module.exports = {
    apiUrl: process.env.API_URL || 'http://localhost:3000',
    apiKey: process.env.API_KEY || 'defaultApiKey'
};

// app.js
const config = require('./config');

console.log(`API URL: ${config.apiUrl}`);
console.log(`API Key: ${config.apiKey}`);