Right now, what I want to do is write an Array.prototype function union( array_to_union ), and I want to call it like this below:
var a = [1,2,3]; a.union([2,3,4]).union([1,3,4]) ...... and the result will be the union of those array, I wonder how can I do that?
I only know I should use Array.prototype.union = function( array_to_union){.....}.
How about this:
Array.prototype.union = function (second) { return second.reduce(function (array, currentValue) { if (this.indexOf(currentValue) === -1) array.push(currentValue); return array; }, this).sort(); }; var a = [1,2,3]; a = a.union([2,3,4]).union([1,3,4]); a = [1, 2, 3, 4] It also sorts the array, as your examples showed in the comments.
Union function that can be chained together:
Array.prototype.union = function(array_to_union) { for (i = 0; i < array_to_union.length; i++) { this.push(array_to_union[i]); } return this; } var a = [1,2,3]; a.union([4,5,6]).union([7,8,9]); Note: in this case, the union function just adds 1 array onto the other (does not care about sorting or distinct values).
JS fiddle with more examples: http://jsfiddle.net/enW2Y/1/
concat() does btw ?
returnthe array instance in your union function.unionfunction supposed to do?concat()