Remove duplicate element from array in javascript Or remove duplicate element after concat in javascript

remove-duplicate.js

Array.prototype.unique = function() {
    var a = this.concat();
    for(var i=0; i<a.length; ++i) {
        for(var j=i+1; j<a.length; ++j) {
            if(a[i] === a[j])
                a.splice(j--, 1);
        }
    }
    return a;
};

/*****************************************
 * var x=['1','2','3','3','4','5','5','0','5'];
 * x.unique();
 * This will return a array like ["1", "2", "3", "4", "5", "0"]
 ***************************************** /