去重 es5 VS es6

 1、數組去重的方式
//1循環一次 
 var arr1 = [1,2,3,44,44,11,2,3,333,3,3];
    function removeRepeat(arr){
        var removeArr = [],obj = {};
        for(var i = 0, l = arr.length; i < l; i++){
            if(!obj[arr[i]]){
                removeArr.push(arr[i]);
                obj[arr[i]] = 1;
            }
        };
        return removeArr;
    }
    var singleArr = removeRepeat(arr1);
    console.log(singleArr); //[1, 2, 3, 44, 11, 333]

function unique(arr){ var obj = {} var result = [] for(var i in arr){ if(!obj[arr[i]]){ obj[arr[i]] = true; result.push(arr[i]); } } return result; }

 function remove2(arr){
        return Array.from(new Set(arr));
    }
    var single2 = remove2(arr1);
    console.log(single2)  //[1, 2, 3, 44, 11, 333] es6 語法  其實問數組的去重主要是考上面一種思惟方式
2、返回字符串中字符出現次數最多的那字符

var str = "abbcccddddfffffgggggg";

    function maxNum(str){

        if(str.length <= 1){
            return str;
        }

        var a1 = str.split(''),obj = {},result = [];
        //利用上面一個數組去重的思想
        for(var k = 0, l = a1.length; k < l; k++){
            if(!obj[a1[k]]){
                obj[a1[k]] = 1;
            }else {
                obj[a1[k]] += 1;
            };
        }

        var num = 0, word = "";
        for(var item in obj){
            if(obj[item] > num){
                num = obj[item];
                word = item;
            }
        }
        return word;
    }
    var w = maxNum(str);
    console.log(w);   //g