如何在UnderscoreJS或angularJS中獲得數組的差異

Question

我有兩個對象數組：

1) [{id:1}{id:2}{id:3}{id:4}{id:5}]

2) [{id:1}{id:2}{id:3}]

UnderscoreJS或AngularJS中的構建函數中是否有任何函數，它們會將輸出顯示為：

[{id:4}{id:5}]

我嘗試使用_.difference和_.without但是這不起作用，因為它們適用於簡單數組而不適用於對象數組

提前致謝。

Answer 1

function diff(a, b) {
  return _.filter(a, function(val) {
    return !_.findWhere(b, val);
  });
}

diff[{id:1}, {id:2}, {id:3}, {id:4}, {id:5}], [{id:1}, {id:2}, {id:3}]); // [{id:4}, {id:5}]

此解決方案特定於此數據結構，不適用於任何對象數組。

Answer 2

我有一個愚蠢的方法，但這似乎可以解釋問題。

//arr1.length >= arr2.length
function diff(arr1,arr2){
    var array1 = new Array();
    var array2 = new Array();
    array1 = array1.concat(arr1);
    array2 = array2.concat(arr2);
    for (var i = array1.length - 1; i >= 0; i--) {
        //instead "id" or other
        var idVal = array1[i].id;
        for (var j = array2.length - 1; j >= 0; j--) {
            if(idVal == array2[j].id) {
                //delete the object in array1 and array2
                array1.del(i);
                array2.del(j);
            };
        };
    };
    return array1.concat(array2);
}

Array.prototype.del = function ( dx ) {
    if (isNaN(dx) || dx > this.length) {
        return false;
    }
    for (var i = 0, n = 0; i < this.length; i++) {
        if (this[i] != this[dx]) {
            this[n++] = this[i]
        }
    }
    this.length -= 1
}

Array.prototype.unique = function () {
    var r = new Array();
    label:for(var i = 0, n = this.length; i < n; i++) {
        for(var x = 0, y = r.length; x < y; x++) {
            if(r[x].id == this[i].id) {
                continue label;
            }
        }
        r[r.length] = this[i];
    }
    return r;
}

var array1 = [{id:"1"},{id:"2"},{id:"3"},{id:"4"},{id:"12"},{id:"15"},{id:"15"}].unique();
var array2 = [{id:"1"},{id:"2"},{id:"03"},{id:"4"},{id:"5"},{id:"5"},{id:"5"},{id:"5"},{id:"5"}].unique();
var resultArray = array1.length >= array2.length 
                  ? diff(array1,array2) : diff(array2,array1);
console.log(resultArray);
//[ { id: '3' },{ id: '12' },{ id: '15' },{ id: '03' },{ id: '5' } ]