JS數組對象去重（4種方法）

問題：數組對象去重

var arr = [{name: 'a',id: 1}, {name: 'a',id: 2}, {name: 'b',id: 3}, {name: 'c',id: 4}, {name: 'c',id: 6}, {name: 'b',id: 6}, {name: 'd',id: 7}];
對數組對象name進行去重處理， 結果顯示為：
[{name: 'a',id: 1}, {name: 'b',id: 3}, {name: 'c',id: 4}, {name: 'd',id: 7}];

方法一：es5冒泡排序法，去重arr

var arr = [{name: 'a',id: 1}, {name: 'a',id: 2}, {name: 'b',id: 3}, {name: 'c',id: 4},
 {name: 'c',id: 6}, {name: 'b',id: 6}, {name: 'd',id: 7}];
function deWeight() {
    for (var i = 0; i < arr.length - 1; i++) {
        for (var j = i + 1; j < arr.length; j++) {
            if (arr[i].name == arr[j].name) {
                arr.splice(j, 1);
                //因為數組長度減小1，所以直接 j++ 會漏掉一個元素，所以要 j--
                j--;
            }
        }
    }
    return arr;
}
var newArr = deWeight();
console.log('%c%s', 'color:red;', '方法一：es5,newArr', newArr);

方法二：es5新建數據雙重循環，去重arr2

var arr2 = [{name: 'a',id: 1}, {name: 'a',id: 2}, {name: 'b',id: 3}, {name: 'c',id: 4},
 {name: 'c',id: 6}, {name: 'b',id: 6}, {name: 'd',id: 7}];
var temp = [];
function deWeightTwo() {
    arr2.forEach(function(a) {
        var check = temp.every(function(b) {
            return a.name !== b.name;
        })
        check ? temp.push(a) : ''
    })
    return temp;
}
var newArr2 = deWeightTwo();
console.log('%c%s', 'color:red;', '方法二：es5,newArr2', newArr2);

方法三：es6的Map()，去重arr3

var arr3 = [{name: 'a',id: 1}, {name: 'a',id: 2}, {name: 'b',id: 3}, {name: 'c',id: 4},
 {name: 'c',id: 6}, {name: 'b',id: 6}, {name: 'd',id: 7}];
let deWeightThree = () => {
    let name = 'name';
    let map = new Map();
    for (let item of arr3) {
        if (!map.has(item.name)) {
            map.set(item.name, item);
        }
    }
    return [...map.values()];
}
let newArr3 = deWeightThree();
console.log('%c%s', 'color:red;', '方法三：es6,newArr3', newArr3);

方法四：es5，對象法去重arr4

var arr4 = [{name: 'a',id: 1}, {name: 'a',id: 2}, {name: 'b',id: 3}, {name: 'c',id: 4},
 {name: 'c',id: 6}, {name: 'b',id: 6}, {name: 'd',id: 7}];
// array.reduce(function(total, currentValue, currentIndex, arr), initialValue)
// (function(必選初始值或計算結束返回值, 必選當前元素, 可選索引, 可選原數組),可選函數初始值)
var obj = {};
function deWeightFour() {
    arr4 = arr4.reduce(function(a, b) {
        obj[b.name] ? '' : obj[b.name] = true && a.push(b);
        return a;
    }, [])
    return arr4;
}
var newArr4 = deWeightFour();
console.log('%c%s', 'color:red;', '方法四：es5,newArr4', newArr4);