数组去重

// 原生方法

Array.prototype.unique = function(){

var res = [], json ={};
for(var i=0; i<this.length; i++){
	if(!json[this[i]]){
		res.push(this[i])
		json[this[i]] = 1;
	}
}
return res

}

arr = ['aaa','abd','aaa',3,2,1,3,2,3,1,1,4]

console.log(arr.unique())

// es6

let arr = [1, 2, 2, 3];

let set = new Set(arr);

let newArr = Array.from(set);

console.log(newArr); // [1, 2, 3]