Many web development frameworks built upon this concept of routes by supplying a router, and object that would store route patterns and perform the routing operation. One popular Node library express, is at its heart a router. If we were to write our Node blog using Express, the syntax to create our routes would be:

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

// Home page 
app.get('/', serveHome);

// Posts 
app.get('posts/', servePosts);
app.get('posts/:id', servePost);'posts/', createPost);'posts/:id', updatePost);
app.delete('posts/:id', deletePost);

// Comments
app.get('posts/:post_id/comments', servePosts);
app.get('posts/:post_id/comments/:id', servePost);'posts/:post_id/comments', createPost);'posts/:post_id/comments/:id', updatePost);
app.delete('posts/:post_id/comments/:id', deletePost);

module.exports = app;

The app variable is an instance of the express Application class, which itself is a wrapper around Node’s http.Server class. The Express Application adds (among other features), routing using the route methods app.get(),, app.put(), and app.delete(). These take routes either in string or regular expression form, and the wildcard values are assigned to an object in req.params. For example, we might write our servePost() method as:

servePost(req, res) {
    var id =;
    var post = db.prepare("SELECT * FROM posts WHERE ID = ?", id);
    // TODO: Render the post HTML

The parameter name in params is the same as the token after the : in the wildcard.

Routers can greatly simplify the creation of web applications, and provide a clear and concise way to specify routes. For this reason, they form the heart of most dynamic web development frameworks.