如何在 JavaScript 中将一个变量值分配给新的变量值

Question

我试图创建一个新的动态数组。我将一个动态变量值分配给另一个新变量并推送新数组。但是更新最后一个数组变量值。

法典

for(let i=0;i<allItems.length;i++){              
            let categories = allItems[i].categories;
                for(let j=0;j<categories.length;j++){
                    let categoryId = categories[j].id;
                    //console.log("categories[j].id ", categoryId);
                    allItems[i]['categoryId'] = categoryId;
                        reitems.push(allItems[i]);
            }
}

我的 JSON 值：

[{
    "itemName" : "3 SS Finish Baskets",
    "itemDesc" : "3 SS Finish Baskets",
    "itemId" : 1,
    "unitId" : 2,
    "categories" : [ 
        {
            "id" : 1,
            "text" : "single room"
        },
        {
            "id" : 2,
            "text" : "Foyer/Living"
        } 
    ]
},
{
....
}]

输出

[{
    "itemName" : "3 SS Finish Baskets",
    "categoryId " : 2
},
{
    "itemName" : "3 SS Finish Baskets",
    "categoryId " : 2
}]

预期输出

[{
    "itemName" : "3 SS Finish Baskets",
    "categoryId " 1
},
{
    "itemName" : "3 SS Finish Baskets",
    "categoryId " 2
}]

Answer 1

试试这段代码，它会起作用。

let allItems = data;
        let reitems = [];
        let n = 0;
        let allItemCategory = data.categories;

            for(let i=0; i<allItems.length; i++){
                allItems[i].categories.forEach(element => {
                    console.log('element.id',element.id)
                    let categoryId = element.id;
                    var obj = {
                        categoryId : element.id,
                        itemName : allItems[i].itemName,
                        itemDesc : allItems[i].itemDesc
                    }
                    reitems[n] = obj;
                    n++;
                });
            }
            console.log('allI new reitems ------->', reitems);

Answer 2

浅拷贝的问题，它正在分配数组的引用。

使用 angular.copy(源、目标(进行深度复制。

  var allItems = [{
    "itemName" : "3 SS Finish Baskets",
    "itemDesc" : "3 SS Finish Baskets",
    "itemId" : 1,
    "unitId" : 2,
    "categories" : [ 
      {
        "id" : 1,
        "text" : "single room"
      },
      {
        "id" : 2,
        "text" : "Foyer/Living"
      } 
    ]
  }]
  $scope.reitems = [];
  for(let i=0;i<allItems.length;i++){              
    let categories = allItems[i].categories;
    for(let j=0;j<categories.length;j++){
      let temp = {};
      angular.copy(allItems[i], temp);
      temp['categoryId'] = categories[j].id;
      $scope.reitems.push(temp);
    }
  }