Run results for: random

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:64.0) Gecko/20100101 Firefox/64.0

Browser: Firefox 64

Operating system: Windows

Device Platform: Desktop

Date tested: 5 years ago

Test name	Executions per second
randomId	14.4 Ops/sec
randomid2	166641.7 Ops/sec

Script Preparation code:

var possibilities = {
    lowerCased: 'abcdefghijklmnopqrstuvwxyz',
    capitals: 'ABCDEFGHIJKLMNOPQRSTUVWXYZ',
    numbers: '0123456789',
    special: '~!@#$%^&()_+-={}[];\','
};

function randomId(len, pattern) {
    if (!len) len = 30;
    if (!pattern) pattern = 'aA0';

    var chars = '';

    pattern.split('').forEach((a) => {
        if (!isNaN(parseInt(a))) {
            chars += possibilities.numbers;
        } else if (/[a-z]/.test(a)) {
            chars += possibilities.lowerCased;
        } else if (/[A-Z]/.test(a)) {
            chars += possibilities.capitals;
        } else {
            chars += possibilities.special;
        }
    });

    var result = '';

    for (var i = 0; i < len; i++) {
        result += chars.charAt(Math.floor(Math.random() * chars.length));
    }

    return result;
}

function randomId2(len = 30, pattern = 'aA0') {
  let chars = '';
  let pl = pattern.length;
  while (pl--) {
    const ch = pattern[pl];
    if (!isNaN(ch)) {
      chars += possibilities.numbers;
    } else if (ch === ch.toLowerCase() && ch !== ch.toUpperCase()) {
      chars += possibilities.lowerCased;
    } else if (ch !== ch.toLowerCase() && ch === ch.toUpperCase()) {
      chars += possibilities.capitals;
    } else {
      chars += possibilities.special;
    }
  }
  
  let result = '';
  const cl = chars.length;
  let i = cl;
  while (i--) {
    result += chars[Math.floor(Math.random() * cl)];
  }
  
  return result;
}

Tests:

randomId
randomId(1000000, 'aA0-');
randomid2
randomId2(1000000, 'aA0-');

randomId

randomid2