1-10 respond to client content according to different URLs

According to url Content of response client

const http = require('http')
// **1.  Import http modular **
// **2.  establish web Server instance **

const server = http.createServer()
    // **3.  Bind to the server instance request event , Listen for client requests **
server.on('request', (req, res) => {
    // Obtain requested url Address 
    const url = req.url
        // Set the default response content to 404 not found
    let content = '<h1>404 not found</h1>'
        // Judge whether the user's request is  / perhaps index.html home page 
        // Judge whether the user's request is  /about.html
    if (url == '/' || url == '/index.html') {
        content = '<h1> home page </h1>'
    } else if (url == '/about.html') {
        content = '<h1> About </h1>'
    }
    // Set up  Content-type  Response head , Prevent Chinese miscoding 
    res.setHeader('Content-Type', 'text/html;charset=utf-8')
        // Use res.end() Respond the content to the client 
    res.end(content)

})
server.listen(80, () => {
    console.log('server running at http://127.0.0.1')
})