Generate a random password from as many keys as there are on a standard US layout keyboard.

genpass.js

#!/usr/bin/env node

var chars =
    [ 'abcdefghijklmnopqrstuvwxyz'
    , 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    , '1234567890'
    , '~!@#$%^&*()_a+'
    , '`-='
    , '[]{}o\'O",./<>?'
    ].join();

var secret = ''
  , length = parseInt(process.argv[process.argv.length - 1]) || 30;
for (var i = 0; i < length; ++i) {
    secret = secret + chars[Math.floor(Math.random() * chars.length)];
}

console.log(secret);