如何验证某个对象属性是必需的？

function validateRequired(obj, requiredFields) {
    let errors = [];
    for (let field of requiredFields) {
        if (!obj.hasOwnProperty(field) || obj[field] === undefined || obj[field] === null || obj[field] === '') {
            errors.push(`${field} is required`);
        }
    }
    return errors;
}

// 使用示例
let obj = { name: 'John', age: null };
let requiredFields = ['name', 'age'];
let errors = validateRequired(obj, requiredFields);
if (errors.length > 0) {
    console.log(errors); // 输出: ["age is required"]
}

const express = require('express');
const app = express();
app.use(express.json());

function validateRequired(req, res, next) {
    let errors = [];
    if (!req.body.name) {
        errors.push('Name is required');
    }
    if (!req.body.age) {
        errors.push('Age is required');
    }
    if (errors.length > 0) {
        return res.status(400).json({ errors });
    }
    next();
}

app.post('/user', validateRequired, (req, res) => {
    res.json(req.body);
});

app.listen(3000, () => console.log('Server running on port 3000'));