Get password from input using node.js - input

Question

How to get password from input using node.js? Which means you should not output password entered in console.

Answer 1

You can use the read module (disclosure: written by me) for this:
In your shell:
npm install read
Then in your JS:
var read = require('read')
read({ prompt: 'Password: ', silent: true }, function(er, password) {
console.log('Your password is: %s', password)
})

Answer 2

Update 2015 Dec 13: readline has replaced process.stdin and node_stdio was removed from Node 0.5.10.
var BACKSPACE = String.fromCharCode(127);
// Probably should use readline
// https://nodejs.org/api/readline.html
function getPassword(prompt, callback) {
if (prompt) {
process.stdout.write(prompt);
}
var stdin = process.stdin;
stdin.resume();
stdin.setRawMode(true);
stdin.resume();
stdin.setEncoding('utf8');
var password = '';
stdin.on('data', function (ch) {
ch = ch.toString('utf8');
switch (ch) {
case "\n":
case "\r":
case "\u0004":
// They've finished typing their password
process.stdout.write('\n');
stdin.setRawMode(false);
stdin.pause();
callback(false, password);
break;
case "\u0003":
// Ctrl-C
callback(true);
break;
case BACKSPACE:
password = password.slice(0, password.length - 1);
process.stdout.clearLine();
process.stdout.cursorTo(0);
process.stdout.write(prompt);
process.stdout.write(password.split('').map(function () {
return '*';
}).join(''));
break;
default:
// More passsword characters
process.stdout.write('*');
password += ch;
break;
}
});
}
getPassword('Password: ', (ok, password) => { console.log([ok, password]) } );

Answer 3

To do this I found this excellent Google Group post
Which contains the following snippet:
var stdin = process.openStdin()
, stdio = process.binding("stdio")
stdio.setRawMode()
var password = ""
stdin.on("data", function (c) {
c = c + ""
switch (c) {
case "\n": case "\r": case "\u0004":
stdio.setRawMode(false)
console.log("you entered: "+password)
stdin.pause()
break
case "\u0003":
process.exit()
break
default:
password += c
break
}
})

Answer 4

Here is my tweaked version of nailer's from above, updated to get a callback and for node 0.8 usage:
/**
* Get a password from stdin.
*
* Adapted from <http://stackoverflow.com/a/10357818/122384>.
*
* #param prompt {String} Optional prompt. Default 'Password: '.
* #param callback {Function} `function (cancelled, password)` where
* `cancelled` is true if the user aborted (Ctrl+C).
*
* Limitations: Not sure if backspace is handled properly.
*/
function getPassword(prompt, callback) {
if (callback === undefined) {
callback = prompt;
prompt = undefined;
}
if (prompt === undefined) {
prompt = 'Password: ';
}
if (prompt) {
process.stdout.write(prompt);
}
var stdin = process.stdin;
stdin.resume();
stdin.setRawMode(true);
stdin.resume();
stdin.setEncoding('utf8');
var password = '';
stdin.on('data', function (ch) {
ch = ch + "";
switch (ch) {
case "\n":
case "\r":
case "\u0004":
// They've finished typing their password
process.stdout.write('\n');
stdin.setRawMode(false);
stdin.pause();
callback(false, password);
break;
case "\u0003":
// Ctrl-C
callback(true);
break;
default:
// More passsword characters
process.stdout.write('*');
password += ch;
break;
}
});
}

Answer 5

How to use read without a callback
With async/await, we can get rid of the annoying callback with the following standard pattern:
const readCb = require('read')
async function read(opts) {
return new Promise((resolve, reject) => {
readCb(opts, (err, line) => {
if (err) {
reject(err)
} else {
resolve(line)
}
})
})
}
;(async () => {
const password = await read({ prompt: 'Password: ', silent: true })
console.log(password)
})()
The annoyance is that then you have to propagate async/await to the entire call stack, but it is generally the way to go, as it clearly marks what is async or not.
Tested on "read": "1.0.7", Node.js v14.17.0.
TODO how to prevent EAGAIN error if you try to use stdin again later with fs.readFileSync(0)?
Both read and https://stackoverflow.com/a/10357818/895245 cause future attempts to read from stdin with fs.readFileSync(0) to break with EAGAIN. Not sure how to fix that. Reproduction:
const fs = require('fs')
const readCb = require('read')
async function read(opts) {
return new Promise((resolve, reject) => {
readCb(opts, (err, line) => {
resolve([err, line])
})
})
}
;(async () => {
const [err, password] = await read({ prompt: 'Password: ', silent: true })
console.log(password)
console.log(fs.readFileSync(0).toString())
})()
or:
#!/usr/bin/env node
const fs = require('fs')
var BACKSPACE = String.fromCharCode(127);
// Probably should use readline
// https://nodejs.org/api/readline.html
function getPassword(prompt, callback) {
if (prompt) {
process.stdout.write(prompt);
}
var stdin = process.stdin;
stdin.resume();
stdin.setRawMode(true);
stdin.resume();
stdin.setEncoding('utf8');
var password = '';
stdin.on('data', function (ch) {
ch = ch.toString('utf8');
switch (ch) {
case "\n":
case "\r":
case "\u0004":
// They've finished typing their password
process.stdout.write('\n');
stdin.setRawMode(false);
stdin.pause();
callback(false, password);
break;
case "\u0003":
// Ctrl-C
callback(true);
break;
case BACKSPACE:
password = password.slice(0, password.length - 1);
process.stdout.clearLine();
process.stdout.cursorTo(0);
process.stdout.write(prompt);
process.stdout.write(password.split('').map(function () {
return '*';
}).join(''));
break;
default:
// More passsword characters
process.stdout.write('*');
password += ch;
break;
}
});
}
async function read(opts) {
return new Promise((resolve, reject) => {
getPassword(opts, (err, line) => {
resolve([err, line])
})
})
}
;(async () => {
const [err, password] = await read('Password: ')
console.log(password)
console.log(fs.readFileSync(0).toString())
})()
Error:
fs.js:614
handleErrorFromBinding(ctx);
^
Error: EAGAIN: resource temporarily unavailable, read
at Object.readSync (fs.js:614:3)
at tryReadSync (fs.js:383:20)
at Object.readFileSync (fs.js:420:19)
at /home/ciro/test/main.js:70:18
at processTicksAndRejections (internal/process/task_queues.js:95:5) {
errno: -11,
syscall: 'read',
code: 'EAGAIN'
}
Asked at: https://github.com/npm/read/issues/39