Nodejs Utililty Methods Array Intersect

Array.prototype.intersect =
  function(otherArray) [ i for each( i in this ) if( otherArray.has( i ) ) ];

Array.prototype.intersect = function(a) {
    return this.filter(function(x) {
  return a.indexOf(x) >= 0;
    });

Array.intersect = function(a, b){
     return a.uniquelize().each(function(o){return b.contains(o) ? o : null});
};

Array.prototype.intersect = function(ar) {
  var results = [];
  for (var i = 0, len = this.length; i < len; i++) {
    for (var j = 0, len2 = ar.length; j < len2; j++) {
      if (this[i] === ar[j]) {
        var found = false;
        for (var k = 0, len3 = results.length; k < len3; k++) {
          if (ar[j] === results[k]) {
            found = true;
...

Array.prototype.intersect = function (arr) {
  return this.filter(function (el, idx) {
    return arr.indexOf(el) >= 0;
  }).unique();
};

Array.prototype.intersect = function (arr, comparer) {
  comparer = comparer || EqualityComparer;
  return this.distinct(comparer).where(function (t) {
    return arr.contains(t, comparer);
  });
};

Array.prototype.intersect = function (array) {
    array = Array.isArray(array) ? array : [];
    return this.filter(function (n) {
        return array.indexOf(n) != -1;
    });
};

Array.prototype.intersect = function(array){
  return(this.filter(function(n){ return array.include(n); }));
};

Array.prototype.intersect = function(array) {
  return this.filter((x) => array.indexOf(x) != -1);
};

Array.prototype.intersect = function(array){
  if(this.length>array.length) return '';
  var equals = true,
      concat = '';
  for(var i = 0; i < this.length-1; i++){
    if(this[i+1] != array[i]){
      equals = false;
      break;
  if(equals){
    concat = this.reduce((acc,k,i) => acc + (i<this.length?k:''), '');
    concat = array.reduce((acc,k,i) => acc + (i>=this.length-1?k:''), concat);
    return concat;
  return '';