JS array polyfill to get all occurrence of an item in a array. (while loop and for Loop)

getIndicesOfFor.js

/** 
  *Simpler solution using for loop; without using any array.indexOf()
  */

Array.prototype.getIndicesOf  = function(item){
  var indices = [];
  
  for(var i=0; i < this.length; i++){
    if(this[i] === item){
      indices.push(i);
    }
  }
  
  return indices;
};

getIndicesOfWhile.js

Array.prototype.getIndicesOf  = function(item){
  var indices = [];
  var currentIndex = 0;
  
  while(currentIndex != -1){
    currentIndex = this.indexOf(item, currentIndex);
    
    if(currentIndex != -1) {
      indices.push(currentIndex);
      currentIndex++;
    }
  }
  
  return indices;
};