Here you can find the source of copy()
//Array extensions Array.prototype.copy = function(){ return this.slice(0); }
Array.dim = function (n, e) { var a = [], i; for (i = 0; i < n; i += 1) { a[i] = e; return a; Array.prototype.copy = function () { return this.slice(0); ...
Array.prototype.copy = function(){ return this.filter(function(){return true;}); };
Array.prototype.copy = function () { return this.slice(0);
Array.prototype.copy = function() { var copy = []; this.forEach(function(element) { copy.push(element); }); return copy; };
Array.prototype.copy = function() { var rst = []; for (var i = 0; i < this.length; ++i) rst.push(this[i]); return rst;
Array.prototype.copy = function() { var newArray = []; for(var index = 0; index < this.length; index++) { newArray.push(this[index]); return newArray; };
Array.prototype.copy = function(t) r = []; this.forEach(function (item) { r.push(item); }); return r;