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Express.js | app.METHOD() Function

  • Last Updated : 18 Jun, 2020

The app.METHOD() function is used to route an HTTP request, where METHOD is the HTTP method of the request, such as GET, PUT, POST, and so on, in lowercase. Thus, the actual methods are app.get(), app.post(), app.put(), and so on.

Syntax:

app.METHOD(path, callback [, callback ...])

Parameters:

  1. Path: The path for which the middleware function is invoked and can be any of:
    • A string representing a path.
    • A path pattern.
    • A regular expression pattern to match paths.
    • An array of combinations of any of the above.
  2. Callback: Callback functions can be:



    • A middleware function.
    • A series of middleware functions (separated by commas).
    • An array of middleware functions.
    • A combination of all of the above.

Installation of express module:

  1. You can visit the link to Install express module. You can install this package by using this command.
    npm install express
  2. After installing express module, you can check your express version in command prompt using the command.
    npm version express
  3. After that, you can create a folder and add a file for example, index.js. To run this file you need to run the following command.
    node index.js

Filename: index.js




var express = require('express');
var app = express();
var PORT = 3000;
  
// Handling GET Request
app.get('/user', function(req, res){
    res.send("Handled GET Request");
});
  
// Handling POST Request
app.post('/user', function(req, res){
    res.send("Handled POST Request");
});
  
// Handling DELETE Request
app.delete('/remove', function(req, res){
    res.send("Handled DELETE Request");
});
  
app.listen(PORT, function(err){
    if (err) console.log("Error in server setup");
    console.log("Server listening on Port", PORT);
});

Steps to run the program:

  1. The project structure will look like this:
  2. Make sure you have installed express module using the following command:
    npm install express
  3. Run index.js file using below command:
    node index.js

    Output:

    Server listening on Port 3000
    

So this is how you can use the express app.METHOD() function which is the HTTP method of the request, such as GET, PUT, POST, and so on, in lowercase.

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