Node.js Error: Cannot GET/ from running the url on the web browser

Problem Statement: On running a Node.js application URL on the web browser it throws the following error: 

Cannot GET/ 

Example: Let’s create a simple Node.js application that throws the same error.

Step 1: Initializes NPM: Create and Locate your project folder in the terminal & type the command

npm init -y

It initializes our node application & makes a package.json file.

Step 2: Install Dependencies: Locate your root project directory into the terminal and type the command

npm install express

To install Express as dependencies inside your project

Step 3: Create Server File: Create an ‘app.js’ file, inside this file require an express Module, and create a constant ‘app’ for creating an instance of the express module.

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

Step 4: Create a Message Route: Create a get route using app.get() method which sends “hello” as a text to the web browser.

app.get("/messages", (req, res) => {
   res.send("Hello");
});

Step 5: Set up a port to run our server: We will do it by using the express, app.listen() method.

app.listen(3000, () => {
  console.log("listening on http://localhost:3000");
})

Complete Code:

Javascript

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

app.get("/messages", (req, res) => {
    res.send("Hello");
});

app.listen(3000, () => {
    console.log("listening on http://localhost:3000");
})

Output:

Reason: Since in the server file, we create a get route for ‘/messages’ URL but inside the browser, we try to get the ‘/’ URL which is not specified in our server file that’s why it throws the error.

Solution Approach: We have to set up a universal route, and when any route or URL which are not specified inside the server file will call then the universal URL sends a “404 URL NOT FOUND” message.

app.get("/:universalURL", (req, res) => {
   res.send("404 URL NOT FOUND");
});

Complete Code:

Javascript

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

app.get("/messages", (req, res) => {
    res.send("Hello");
});

app.get("/:universalURL", (req, res) => {
    res.send("404 URL NOT FOUND");
});

app.listen(3000, () => {
    console.log("listening on http://localhost:3000");
})

Output: