JavaScript Create all possible Combination string from a given Input string : Example of Permutation

permutation.js

// First way

function swap (alphabets, index1, index2) {
  var temp = alphabets[index1];
  alphabets[index1] = alphabets[index2];
  alphabets[index2] = temp;
  return alphabets;
}

function permute (alphabets, startIndex, endIndex) {
  if (startIndex === endIndex) {
	console.log(alphabets.join(''));
  } else {
    var i;
    for (i = startIndex; i <= endIndex; i++) {
      swap(alphabets, startIndex, i);
      permute(alphabets, startIndex + 1, endIndex);
      swap(alphabets, i, startIndex); // backtrack
    }
  }
}

Output >
var alphabets = ['A','B','C'];
permute(alphabets, 0, alphabets.length -1 );
 ABC
 ACB
 BAC
 BCA
 CBA
 CAB

 // Second way

function getAllPermutations(string) {
  var results = [];
  if (string.length === 1) {
    results.push(string);
    return results;
  }
  for (var i = 0; i < string.length; i++) {
    var firstChar = string[i];
    var charsLeft = string.substring(0, i) + string.substring(i + 1);
    var innerPermutations = getAllPermutations(charsLeft);
    for (var j = 0; j < innerPermutations.length; j++) {
      results.push(firstChar + innerPermutations[j]);
    }
  }
  return results;
}

Ouput >
  getAllPermutations("ABC")
 ["ABC", "ACB", "BAC", "BCA", "CAB", "CBA"]