code snippet to generate password

passwordGenerator.js

/**
 * Function
 * @param {Number} seed length of sequence of characters generated 
 * @returns {String} sequence of Capital letters
 */
let generateCaps = (seed) => {
    // randaomly select letters withing ascii characters
    var string = '';
    for (let i = 0; i <= seed; i++) {
     // select randomNumber
      var capLetter = Math.floor(Math.random() * 26) + 65;
    // convert number to caps
      string += String.fromCharCode(capLetter);
    }
    return string;
  };
  /**
   * Function generates a sequence of characters
   * @param {Number} seed length of sequence of characters generated 
   * @returns {String} a sequence of numbers
   */
  let generateNums = (seed) => {
    var string = '';
    for (let i = 0; i <= seed; i++) {
      var number = Math.floor(Math.random() * 10);
      string += number;
    }
    return string;
  };

  /**
   * Function generates a sequence of characters
   * @returns {String} returns a sequence of special characters.
   */
  let generateSpecials = () => {
    var arraySpecial = ['@', '#', '$', '!'];
    var index = Math.floor(Math.random() * 4);
    return arraySpecial[index];
  };
/**
 * Generates a sequence of characters
 * @param {Number} seed lenght of characters to generatetr
 * @returns {String} returns a sequence of ascii characters
 */
let generateAny = (seed) => {
     // randaomly select letters withing ascii characters
    var string = '';
    for (let i = 0; i <= seed; i++) {
     // select randomNumber
      var capLetter = Math.floor(Math.random() * 25) + 97;
    // convert number to caps
      string += String.fromCharCode(capLetter);
    }
    return string;
  };
  /**
   * Function to generate password
   * @param {Number} minPassLength minimum passwordLength to generate
   * @param {Array} charcterGenerators array containing funtions that return a sequence of characters
   */
  let generatePassword = (minPassLength, charcterGenerators) => {
    let functions = charcterGenerators;
    let alreadyRan = [];
    let randomString = '';
   // your can add or more generators or pass in pattern as arguments
  // let pattern = /yourpatter/   
    while (1) {
        /* pattern test should replace allFunctionsDidRun 
        * allFunctionsDidRun is used because i could not figure the right regex for 
        * atleast one cap, atleast one num, atleast one special character and atleast a letter , 
        * all of the above appearing in the string in any order.
        */
      if (randomString.length >= minPassLength && allFunctionsDidRun(alreadyRan, functions.length))
        break;
      let selectedIndex = Math.floor(Math.random() * functions.length); 
      if (alreadyRan.indexOf('' + selectedIndex + '') >= 0) {
        if (allFunctionsDidRun(alreadyRan))
          alreadyRan = [];
        continue;
      } else {
        // generate another random string
        let seed = Math.floor(Math.random() * 3);
        // call functions and pass arguments
        randomString += functions[selectedIndex](seed);
        alreadyRan.push('' + selectedIndex + '');
      }
    }
    /**
     * best to use regex ,there exist a possibility that the first 20 characters might not match
     * after a 100 run of the function, the first 20 characters matched pattern but we cannot rely on that.
     * TODO : Opimise function
     */
    if(randomString.length > 20)
        return randomString.substring(0,21);
    return randomString;
  }
  /** Checks if all functions in an array of functions were called
   * @param {Array} alreadyRan contains indices of already ran character generators
   * @param {Number} charcterGeneratorsLength the length of character generators available
   */
  let allFunctionsDidRun = ( alreadyRan, characterGeneratorsLength) => {
        let allRan = true;
        for(let i = 0 ; i < characterGeneratorsLength; i++){
            if(alreadyRan.indexOf('' + i + '') == -1){
                allRan = false;
                break;
            }
        }
        return allRan;
  }
  console.log(generatePassword(10, [generateCaps, generateNums, generateSpecials, generateAny]))