This should do the trick:
Array.prototype.getUnique = function(){
var uniques = [];
for(var i = 0, l = this.length; i < l; ++i){
if(this.lastIndexOf(this[i]) == this.indexOf(this[i])) {
uniques.push(this[i]);
}
}
return uniques;
}
// Usage:
var a = [2, 6, 7856, 24, 6, 24];
alert(JSON.stringify(a.getUnique()));
console.log(a.getUnique()); // [2, 7856]
To check if a specific item is unique in the array, it just checks if the first index it’s found at, matches the last index it’s found at.