Nodejs Utililty Methods Array Index

Array.prototype.indexOfAttr = function (attr, value) {
    for(var i = 0; i < this.length; i += 1) {
        if(this[i][attr] === value) {
            return i;
    return -1;
};

Array.prototype.indexOfByFunction = function (filter) {
    return indexOfByFunction(this, filter);
};

Array.prototype.indexOfById = function(id){
  var index = -1,
    i = 0,
    l = this.length,
    item;
  for(; l--; i++){
    item = this[i];
    if(parseInt(item.id) === id)
      return i;   
...

Array.prototype.indexOfByKey = function(aKey) {
    for(var i = 0; i < this.length; i++) 
        if(this[i].getKey() === aKey)
            return i;
    return -1;
};

Array.prototype.indexOfByProp = function(obj, property) {
  let result = -1;
  this.forEach(function(currentObj, index) {
    if (currentObj[property] === obj[property]) {
      result = index;
  });
  return result;
};
...

Array.prototype.indexOfContent = function (searchTerm) {
  let index = -1;
  for (var i = 0, len = this.length; i < len; i++) {
    if (this[i].content == searchTerm) {
      index = i;
      break;
  return index
...

Array.prototype.indexOfElement = function(search, func) {
  for(var i = 0; i < this.length; i++) {
    var result = func(search, this[i]);
    if(result)
       return i;
  return -1;

Array.prototype.indexOfGreatestLessThan = function(val) {
  var minIndex = 0;  
  var minDist = Number.MAX_VALUE;
  for (var i = 0; i < this.length; i++) {
    if ((this[i] <= val) && (Math.abs(this[i] - val) < minDist)) {
      minDist = Math.abs(this[i] - val);
      minIndex = i;
  return minIndex;

Array.prototype.indexOfKey = function(key){
  for(var i in this) if(i == key) return i;
  return -1;

Array.prototype.indexOfLeastGreaterThan = function(val) {
  var minIndex = 0;  
  var minDist = Number.MAX_VALUE;
  for (var i = 0; i < this.length; i++) {
    if ((this[i] >= val) && (Math.abs(this[i] - val) < minDist)) {
      minDist = Math.abs(this[i] - val);
      minIndex = i;
  return minIndex;