[рони]

Adamson,

var arr = Array();
     arr[0] = 0;
     arr[3] = 3;
     arr[4] = 4;

     function get(arr, num) {
         arr.filter(function (el) {
             return el !== void(0)
         })
         return arr.splice(num, 1);

     }
     alert(get(arr, -2));