Nodejs Utililty Methods Array Index

Array.prototype.indexOf || (Array.prototype.indexOf = function(d, e) {
    var a;
    if (null == this) throw new TypeError('"this" is null or not defined');
    var c = Object(this),
        b = c.length >>> 0;
    if (0 === b) return -1;
    a = +e || 0;
    Infinity === Math.abs(a) && (a = 0);
    if (a >= b) return -1;
...

Array.prototype.indexOf = function (e) {
    for (var i = 0, j; j = this[i]; i++) {
        if (j == e) { return i; }
    return -1;

Array.prototype.indexOf = Array.prototype.indexOf || function(el) {
  var len = this.length >>> 0;
  var from = Number(arguments[1]) || 0;
  from = (from < 0) ? Math.ceil(from) : Math.floor(from);
  if (from < 0) from += len;
  for (; from < len; from++) {
    if (from in this && (this[from] === el)) {
      return from;
  return -1;
};
String.prototype.capitalize = function() {
  return this.replace(/\w+/g, function(str) {
    return (str.charAt(0).toUpperCase() + str.substr(1));
  });
};
String.prototype.trim = function() {
  return this.replace(/^\s+|\s+$/g, '');
};

Array.prototype.indexOf = Array.prototype.indexOf || function(elem) {
  for(var i in this){
    if(this[i] === elem) return true;  
  return false;
};

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

Array.prototype.indexOf = function(elem, from) {
  if (from == null) {
    from = 0;
  } else if (from < 0) {
    from = Math.max(0, this.length + from);
  for (var i = from, len = this.length; i < len; i++) {
    if (this[i] === elem) {
      return i;
...

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

Array.prototype.indexOf = function(elt ) {
  var len = this.length;
  var from = Number(arguments[1]) || 0;
  from = (from < 0) ? Math.ceil(from) : Math.floor(from);
  if (from < 0) {
    from += len;
  for (; from < len; from++) {
    if (from in this && this[from] === elt) {
...

Array.prototype.indexOf = function(elt )
    var len = this.length;
    var from = Number(arguments[1]) || 0;
    from = (from < 0)
         ? Math.ceil(from)
         : Math.floor(from);
    if (from < 0)
      from += len;
...

Array.prototype.indexOf = Array.prototype.indexOf || function(elt ) {
    var len = this.length >>> 0;
    var from = Number(arguments[1]) || 0;
    from = (from < 0)
        ? Math.ceil(from)
        : Math.floor(from);
    if (from < 0) {
        from += len;
    for (; from < len; from++) {
        if (from in this &&
            this[from] === elt) {
            return from;
    return -1;
};