Nodejs Utililty Methods Array Different

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

Array.prototype.diff = function( a ) {
    return this.filter( function( i ) { return !( a.indexOf( i ) > -1 ); } );
};

Array.prototype.diff = function (B) {
    return this.filter(function (a) { return B.indexOf(a) < 0; });
};

Array.prototype.diff = function(a) {
    return this.filter(function(i) {return a.indexOf(i) < 0;});
};

Array.prototype.diff = function (a) {
    return this.filter(function (e) { return a.indexOf(e) === -1 });
};

module.exports = {
    findMissing :function (a,b){
            if(a.length === b.length) return 0;
            if(a.length < b.length) return b.diff(a)[0];
            return a.diff(b)[0];
};
Array.prototype.diff = function(a) {
    return this.filter(function(i) {return a.indexOf(i) < 0;});
...

Array.prototype.diff = function(a) {
    return this.filter(function(i) {return a.indexOf(i) < 0;});
};
function diffArray(arr1, arr2) {
  var newArr = [];
  newArr = arr2.diff(arr1);
  return arr1.diff(arr2).concat(arr2.diff(arr1));
console.log(diffArray([1, 2, 3, 5], [1, 2, 3, 4, 5]));
...

Array.prototype.diff = function(a) {
  return this.filter(function(i) {return !(a.indexOf(i) > -1);});
};

Array.prototype.diff = function(a) {
    return this.filter(function(i) {return a.indexOf(i) < 0;});
};
Array.prototype.contains = function(obj) {
    var i = this.length;
    while (i--) {
        if (this[i] === obj) {
            return true;
    return false;
};
function sym(args) {
   var a = args[0].diff(args[1]).concat(args[1].diff(args[0]));  
   var b = args[0].filter(function(n) {
     return args[1].indexOf(n) != -1;
   });
  return a;
sym([1, 2, 3], [5, 2, 1, 4]);

function getSrv(name) {
  return angular.element(document.body).injector().get(name);
function isNumeric(n) {
  return !isNaN(parseFloat(n)) && isFinite(n);
function inArray(needle, haystack) {
    var length = haystack.length;
    for(var i = 0; i < length; i++) {
...