Node.Js on windows - How to clear console

Question

Being totally new into node.js environment and philosophy i would like answers to few questions. I had downloaded the node.js for windows installer and also node package manager.Windows Cmd prompt is being currently used for running nodejs apps.

1. cls clears the command window or errors in command prompt. Is there a equivalent for node.js ? console.clear does not exist ;( or does it in some other form?

2. I created a server through this code below

   var http = require("http");
   http.createServer(function (request, response) {
       response.writeHead(200, {
           "Content-Type": "text/html"
       });
       response.write("Hello World");
       console.log("welcome world")response.end();
   }).listen(9000, "127.0.0.1");
   

i changed the code to below and refreshed the browser to find that content type does not change, how do i get to see the changes?

var http = require("http");
http.createServer(function(request, response) {
  response.writeHead(200, {"Content-Type": "text/plain"});
  response.write("Hello World");
  console.log("welcome world")
  response.end();
}).listen(9000,"127.0.0.1");

Answer 1

console.log('\033[2J');

This works on linux. Not sure about windows.

You can "trick" the user using something like this:

var lines = process.stdout.getWindowSize()[1];
for(var i = 0; i < lines; i++) {
    console.log('\r\n');
}

Answer 2

process.stdout.write('\033c');

This also works on windows. Win7 at least.

Answer 3

This clears the console on Windows and puts the cursor at 0,0:

var util = require('util');
util.print("\u001b[2J\u001b[0;0H");

or

process.stdout.write("\u001b[2J\u001b[0;0H");

Answer 4

This is for Linux mainly; but is also reported to work in Windows.

There is Ctrl + L in Gnome Terminal that clears the terminal. It can be used with Python, Node JS or any other REPL running in terminal. It has the same effect as clear command.

Answer 5

i am using a windows CMD and this worked for me

console.clear();

Answer 6

And to clear the console while in strict mode on Windows:

'use strict';
process.stdout.write('\x1Bc'); 

Answer 7

Starting from Node.JS v8.3.0 you can use method clear:

console.clear()

Answer 8

Just use CTRL + L on windows to clear the console.

Answer 9

Haven't tested this on Windows but works on unix. The trick is in the child_process module. Check the documentation. You can save this code as a file and load it to the REPL every time you need it.

var exec = require('child_process').exec;

function clear(){
    exec('clear', function(error, stdout, stderr){
        console.log(stdout);
    });    
}

Answer 10

To solve problems with strict mode:

'use strict';
process.stdout.write('\x1B[2J');

Answer 11

Just use the official way:

console.log('Blah blah blah'); // Prints "Blah blah blah"

console.clear(); // Clears, or in other words, resets the terminal.

console.log('You will only see this message. No more Blah blah blah...');

Answer 12

If you're using VSCode you can use CTRL + K. I know this is not a generic solution but may help some people.

Answer 13

Based on sanatgersappa's answer and some other info I found, here's what I've come up with:

function clear() {
    var stdout = "";

    if (process.platform.indexOf("win") != 0) {
        stdout += "\033[2J";
    } else {
        var lines = process.stdout.getWindowSize()[1];

        for (var i=0; i<lines; i++) {
            stdout += "\r\n";
        }
    }

    // Reset cursur
    stdout += "\033[0f";

    process.stdout.write(stdout);
}

To make things easier, I've released this as an npm package called cli-clear.

Answer 14

You can use the readline module:

readline.cursorTo(process.stdout, 0, 0) moves the cursor to (0, 0).

readline.clearLine(process.stdout, 0) clears the current line.

readline.clearScreenDown(process.stdout) clears everything below the cursor.

const READLINE = require('readline');

function clear() {
    READLINE.cursorTo(process.stdout, 0, 0);
    READLINE.clearLine(process.stdout, 0);
    READLINE.clearScreenDown(process.stdout);
}

Answer 15

On package.json try this:

  "nodemonConfig": {
    "events": {
      "start": "clear"
    }
  }

Answer 16

I couldn't get any of the above to work. I'm using nodemon for development and found this the easiest way to clear the console:

  console.log("\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n");

It just scrolls the console several lines so you get a clear screen for subsequent console.log commands.

Hope it helps someone.

Answer 17

This code works fine on my node.js server console Windows 7.

process.stdout.write("\u001b[0J\u001b[1J\u001b[2J\u001b[0;0H\u001b[0;0W");

Answer 18

On mac, I simply use Cmd + K to clear the console, very handy and better than adding codes inside your project to do it.

Answer 19

Belated, but ctrl+l works in windows if you're using powershell :) Powershell + chocolatey + node + npm = winning.

Answer 20

Ctrl + L This is the best, simplest and most effective option.

Answer 21

In my case I did it to loop for ever and show in the console a number ever in a single line:

class Status {

  private numberOfMessagesInTheQueue: number;
  private queueName: string;

  public constructor() {
    this.queueName = "Test Queue";
    this.numberOfMessagesInTheQueue = 0;
    this.main();
  }

  private async main(): Promise<any> {    
    while(true) {
      this.numberOfMessagesInTheQueue++;
      await new Promise((resolve) => {
        setTimeout(_ => resolve(this.showResults(this.numberOfMessagesInTheQueue)), 1500);
      });
    }
  }

  private showResults(numberOfMessagesInTheQuee: number): void {
    console.clear();
    console.log(`Number of messages in the queue ${this.queueName}: ${numberOfMessagesInTheQuee}.`)
  }
}

export default new Status();

When you run this code you will see the same message "Number of messages in the queue Test Queue: 1." and the number changing (1..2..3, etc).