How do I get console input in javascript?

Question

I\'m currently using spidermonkey to run my JavaScript code. I\'m wondering if there\'s a function to get input from the console similar to how Python does this:

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Answer 1

You can try something like process.argv, that is if you are using node.js to run the program.
console.log(process.argv) => Would print an array containing

[                                                                                                                                                                                          
  '/usr/bin/node',                                                                                                                                                                         
  '/home/user/path/filename.js',                                                                                                                                            
  'your_input'                                                                                                                                                                                   
]

You get the user provided input via array index, i.e., console.log(process.argv[3]) This should provide you with the input which you can store.

Example:

var somevariable = process.argv[3]; // input one
var somevariable2 = process.argv[4]; // input two

console.log(somevariable);
console.log(somevariable2);

If you are building a command-line program then the npm package yargs would be really helpful.

Answer 2

In plain JavaScript, simply use response = readline() after printing a prompt.

In Node.js, you'll need to use the readline module: const readline = require('readline')

Answer 3

Good old readline();

See MDN docs: https://developer.mozilla.org/en-US/docs/Mozilla/Projects/SpiderMonkey/Introduction_to_the_JavaScript_shell#readline.28.29

Answer 4

As you mentioned, prompt works for browsers all the way back to IE:

var answer = prompt('question', 'defaultAnswer');

For Node.js > v7.6, you can use console-read-write, which is a wrapper around the low-level readline module:

const io = require('console-read-write');

async function main() {
  // Simple readline scenario
  io.write('I will echo whatever you write!');
  io.write(await io.read());

  // Simple question scenario
  io.write(`hello ${await io.ask('Who are you?')}!`);

  // Since you are not blocking the IO, you can go wild with while loops!
  let saidHi = false;
  while (!saidHi) {
    io.write('Say hi or I will repeat...');
    saidHi = await io.read() === 'hi';
  }

  io.write('Thanks! Now you may leave.');
}

main();
// I will echo whatever you write!
// > ok
// ok
// Who are you? someone
// hello someone!
// Say hi or I will repeat...
// > no
// Say hi or I will repeat...
// > ok
// Say hi or I will repeat...
// > hi
// Thanks! Now you may leave.

Disclosure I'm author and maintainer of console-read-write

For SpiderMonkey, simple readline as suggested by @MooGoo and @Zaz.