learning express step(四)

learning express route function

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

app.get('/', function (req, res) {
    res.send('root');
});

app.get('/about', function (req, res) {
    res.send('about');
});

app.get('/random.txt',function (req, res) {
    res.send('random.txt');
});
//  abc  abd
app.get('/ab?cd',function (req, res) {
    res.send('ab?cd');
});
// abbcd abbbcd and so on
app.get('/ab+cd', function (req, res) {
    res.send('ab+cd');
});
// adRANDOMcd
app.get('/ab*cd', function (req, res) {
    res.send('ab*cd');
});
//. ade adcde
app.get('/ab(cd)?e', function (req, res) {
    res.send("ab(cd)?e");
});

app.listen(,function () {
    console.log("learning express router");
});