arrayUnique.js

(A)Array.prototype.unique = function(){
	return this.filter((value, index, self)=>(
	   self.indexOf(value) === index 
  ));
}
var names = ["dk", "rao","dk","jsk"];
console.log(names.unique());


(B) var j = [...new Set(names)]
console.log(j);

(C) Array.prototype.unique = function(){
        var self = this;
        return this.filter(function(elem, index){
            return self.indexOf(elem) === index;
        })
}
console.log(names.unique());

(D) console.log(Array.from(new Set(names)))


(E) Array.prototype.unique_ = Array.prototype.unique || function() {
        var arr = [];
	this.reduce(function (hash, num) {
		if(typeof hash[num] === 'undefined') {
			hash[num] = 1; 
			arr.push(num);
		}
		return hash;
	}, {});
	return arr;
}
console.log(names.unique_());