Nodejs Utililty Methods Array Intersect

Array.prototype.intersect = function (ary) {
    return this.union(ary).filter(x => this.contains(x) && ary.contains(x));
};

Array.prototype.intersect = function(b) {
  var array = new Array();
  var ua = this.uniquelize();
  var length = ua.length;
  for (var i = 0; i < length; i++) {
    if (b.inArray(ua[i])) {
      array.push(ua[i]);
  return array;
};

Array.prototype.intersect = function(b) {
    var flip = {}, res = [];
    for (var i = 0; i < b.length; i++) flip[b[i]] = i;
    for (i = 0; i < this.length; i++)
        if (flip[this[i]] != undefined) res.push(this[i]);
    return res;

Array.prototype.intersect = function(tab){
    var temp = [];
    for(var i = 0; i < this.length; i++){
        for(var k = 0; k < tab.length; k++){
            if(this[i] == tab[k]){
                temp.push( this[i]);
                break;
    return temp;
};

Array.prototype.intersect = function intersect(otherArray) {
  return this.filter(function(item) {
    return otherArray.has(item);
  });
};

Array.prototype.intersection = function(arr){
  return this.filter(function(n){
    return arr.indexOf(n) != -1;
  });

Array.prototype.intersection = function(arr) {
    var intersection = new Array();
    for (var i = 0; i < arr.length; ++i)
        if (this.contains(arr[i]))
            intersection.push(arr[i]);
    return intersection;

Array.prototype.intersection = function(t)
    var s = this.toHash();
    var t = t.toHash();
    var intersection = [];
    s.keys().forEach(function(item)
        if (t.containsKey(item))
            intersection.push(item);
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