HTTP Methods & URL Binding

What are HTTP methods?

HTTP methods tell the server what the client wants to do with data. In Express, each method has a matching function such as app.get() or app.post(). fileciteturn1file0L4-L7

HTTP Methods at a glance

Route examples

app.get("/users", (req, res) => {
  res.send("List of users");
});

app.post("/users", (req, res) => {
  res.send("New user created");
});

app.put("/users/:id", (req, res) => {
  res.send(`User ${req.params.id} fully replaced`);
});

app.patch("/users/:id", (req, res) => {
  res.send(`User ${req.params.id} partially updated`);
});

app.delete("/users/:id", (req, res) => {
  res.send(`User ${req.params.id} deleted`);
});

One Express app for multiple methods

The source document creates index.js in a hello-world directory and defines GET, POST, PUT and DELETE routes on /. fileciteturn1file0L48-L66

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

app.get('/', function(req, res){
  res.send("GET Request!");
});

app.post('/', function(req, res){
  res.send("POST Request!");
});

app.put('/', function(req, res){
  res.send("PUT Request!");
});

app.delete('/', function(req, res){
  res.send("DELETE Request!");
});

app.listen(3000);

Source document, page 2: the browser displays the GET response at localhost:3000. fileciteturn1file0L74-L76

Testing with Postman

The source demonstrates testing POST and PUT requests in Postman using http://localhost:3000/, with the response body showing the corresponding message. fileciteturn1file0L81-L85

HEAD and OPTIONS

app.head("/profile", (req, res) => {
  res.set("Content-Type", "application/json");
  res.set("Last-Modified", "Sun, 23 Aug 2026 10:00:00 GMT");
  res.status(200).end();
});

app.options("/users", (req, res) => {
  res.set("Allow", "GET, POST, OPTIONS");
  res.status(204).end();
});

Why dynamic routes?

Static routes are fixed. Dynamic routes let you place parameters in the URL so the server can process different values. fileciteturn1file0L120-L125

Single parameter

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

app.get('/:id', function(req, res){
  res.send('The id you specified is ' + req.params.id);
});

app.listen(3000);

Try http://localhost:3000/123. Replacing 123 with another value changes the response because the value is captured as req.params.id. fileciteturn1file0L133-L137

Source document, page 5: a browser request to a dynamic URL displays the supplied ID. fileciteturn1file0L133-L137

Multiple parameters in a URL

Express can capture more than one URL parameter. The source uses /things/:name/:id. fileciteturn1file0L139-L149

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

app.get('/things/:name/:id', function(req, res) {
  res.send('id: ' + req.params.id + ' and name: ' +
           req.params.name);
});

app.listen(3000);

The document emphasizes that the paths shown are different and do not overlap; if code should execute for /things itself, that path must be defined separately. fileciteturn1file0L154-L157

Restricting route parameters with a pattern

You can use a regular expression to restrict what a dynamic parameter is allowed to match. The source example requires the ID to be exactly five digits. fileciteturn1file0L158-L170

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

app.get('/things/:id([0-9]{5})', function(req, res){
  res.send('id: ' + req.params.id);
});

app.listen(3000);

Handling a route that does not match

If none of the defined routes match a request, the source notes that Express can respond with a message such as Cannot GET <your-request-route>. It then demonstrates a final route that can return a custom invalid-URL message. fileciteturn1file0L169-L180

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

// Other routes here

app.get('*', function(req, res){
  res.send('Sorry, this is an invalid URL.');
});

app.listen(3000);

Valid vs invalid example

Source document, page 7: browser screenshots illustrate a valid URL response and an invalid URL response.

Mind map: HTTP methods → routes → parameters

Test yourself

What you should remember

• Express provides method-specific route functions such as app.get() and app.post(). fileciteturn1file0L4-L7
• GET reads, POST creates, PUT replaces, PATCH updates part, and DELETE removes.
• HEAD returns headers/metadata without the response body; OPTIONS can tell the client which methods/options are available. fileciteturn1file0L92-L115
• Dynamic routes use placeholders such as :id and :name. Their values are available through req.params. fileciteturn1file0L125-L136
• Route patterns can restrict which parameter values are accepted. fileciteturn1file0L158-L172
• A catch-all invalid-URL route should come after the other routes. fileciteturn1file0L187-L189