Javascript (node.js) Specific Random String Builder

I'm looking for an efficient way to build a random string that has specific requirements but can vary in length. It must: Contain at least one uppercase character. Contain at leas

Solution 1:

var randomString = (function() {
  // Define character classes to pick from randomly.var uppers = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ';
  var lowers = 'abcdefghijklmnopqrstuvwxyz';
  var numbers = '0123456789';
  var specials = '_-|@.,?/!~#$%^&*(){}[]+=';
  var charClasses = [uppers, lowers, numbers, specials];
  var minLen = charClasses.length;
  functionchooseRandom(x) {
    var i = Math.floor(Math.random() * x.length);
    return (typeof(x)==='string') ? x.substr(i,1) : x[i];
  }
  // Define the function to actually generate a random string.returnfunction(maxLen) {
    maxLen = (maxLen || 36);
    if (maxLen < minLen) { thrownewError('length must be >= ' + minLen); }
    do { // Append a random char from a random char class.var str='', usedClasses={}, charClass;
      while (str.length < maxLen) {
        charClass = chooseRandom(charClasses);
        usedClasses[charClass] = true;
        str += chooseRandom(charClass);
      }
      // Ensure we have picked from every char class.
    } while (Object.keys(usedClasses).length !== charClasses.length);
    return str;
  }
})();

randomString(); // => "o4m3H@YC7j0r@^gsY@1vlg2]cI66|9^beZ1)"randomString(); // => "R6-K0Kq%4O0Je*=iPbVaV|bo-_,,g[j8wTW2"randomString(); // => "!uu5NUWs1P}SRN78l}32Gno$]2m5PV+h+wTG"

Solution 2:

Regex are used to check, capture, split or replace something in a string, you can't build something from zero with them.

However you can make some replacement in a string that contain a random generated number to have that you want.