Nodejs Utililty Methods Array First Predicate

Array.prototype.first = function(f){
    var i = 0;
    while(i < this.length){
        if(f == undefined){
            return this[i];
        if(f(this[i])){
           return this[i];
        i++;
    return null;
};

Array.prototype.first = function(fn) {
    if (Object.prototype.toString.call(this) !== '[object Array]') {
        throw new TypeError("`this` must be Array, not " + typeof this);
    if (typeof fn === 'undefined') {
        return this[0];
    if (typeof fn !== 'function') {
        throw new TypeError("Optional `argument[0]` must be predicate function if defined");
...

Array.prototype.first = function(func) {
  return this.where(func)[0];
};

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

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

Array.prototype.first = function(matching) {
    for (var i = 0; i < this.length; i++) {
  var entry = this[i];
  if (matching(entry) == true)
      return this[i];
    return null;

Array.prototype.first = function (n) {
    'use strict';
    return this.slice(0, n || 1);
};

Array.prototype.first = function(n) {
  if (this.length === 0 || n < 0) return void 0;
  if (n === undefined) return this[0];
  if (n === 0) return [];
  return this.initial(this.length - n);
};

Array.prototype.first = function (num) {
   if (num !== undefined) {
      return this.slice(0, num);
   return this[0];
};

Array.prototype.first = function(predicate) {
    for (var i = 0, l = this.length; i < l; i++) {
        if (predicate(this[i]))
            return this[i];