Nodejs Utililty Methods Array Find

Array.prototype.findBy = function (field, value) {
    return this.filter(function (i) {
        return i[field] === value;
    })[0];
};

Array.prototype.findByField = function(field,value)
  for(var t=0; t<this.length; t++) {
    if(this[t][field] == value)
      return t;
  return null;
};

Array.prototype.findByProp = function(propName, propValue) {
  for(var i = 0 ; i < this.length ; i++) {
    if(this[i][propName] === propValue) {
      return this[i];
};

Array.prototype.findByProperty = function (propName, value) {
    if (this.length > 0) {
        for (var i = this.length - 1; i > -1; i--) {
            var propObj = this[i];
            if (propObj[propName] === value) {
                return propObj;
    return null;
};

Array.prototype.findBySku = function(sku) {
  var result = null;
  this.forEach(function(elem, index) {
    if (elem.sku === sku) {
      result = elem;
  })
  return result;
};
...

Array.prototype.findElement = function(predicate) {
  for (var i=0; i<this.length; ++i) {
    if (predicate(this[i])) {
      return this[i];
Array.prototype.contains = function(element) {
  return this.indexOf(element) != -1;
...

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

Array.prototype.findElements = Array.prototype.findElements || function (config) {
    var i,
    j,
        key,
        keys = [],
        isFound,
        el = null,
        results = [];
    for (key in config) {
...

Array.prototype.findFirst = function(fnCheckCallback, parameter) {
  for (var elementIndex in this) {
    if (this.hasOwnProperty(elementIndex) && fnCheckCallback.apply(this[elementIndex], [elementIndex, parameter])) {
      return this[elementIndex]; 
};

Array.prototype.findFirst = function(fun) {
  for(var i = 0; i < this.length; i=i+1) {
    if(fun(this[i])) {
      return this[i];