express 304

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

app.use(express.static('public', {
    maxAge: '1d',
    etag: true,
    lastModified: true
}));

app.get('/data', (req, res) => {
    const data = { message: 'Hello, World!' };
    res.set('ETag', generateETag(data));
    res.set('Last-Modified', new Date().toUTCString());
    if (req.headers['if-none-match'] === res.get('ETag')) {
        return res.status(304).end();
    }
    res.json(data);
});

function generateETag(data) {
    // 简单示例，实际应用中可以使用更复杂的算法
    return JSON.stringify(data);
}

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