如何将数组的元素添加到另一个对象并计数

Question

首先，我有一个包含如下对象元素的数组：

$scope.selectedIngredient = [object1, object2, object3, object1, object2];

其次，我有一个新对象：

$scope.selectedIngredientResults = {};

现在我想在javascript中实现一个这样的功能：

计算数组的每个对象元素，并将它们放入一个新对象中并存储每个对象

计数

$scope.selectedIngredientResults = [

    {"object" : object1, "count" : 2},
    {"object" : object2, "count" : 2},
    {"object" : object3, "count" : 1}

];

[![这里是新的对象结果，这就是我想要的，

我正在尝试使用

$scope.addIngredient = function(selectedElement) {

console.log('selectedElement', selectedElement);
$scope.selectedIngredient.push(selectedElement);
console.log('$scope.selectedIngredient' , $scope.selectedIngredient);
$scope.selectedIngredientResults = {};
var lengthofR = $scope.selectedIngredient.length;

for (var i = lengthofR - 1; i >= 0; i--) {
    var selected = $scope.selectedIngredient[i]['ingredient_id'];
    console.log('lengthofR', lengthofR);
    if(selected){
        if($scope.selectedIngredientResults.hasOwnProperty(selected)){

            $scope.selectedIngredientResults[$scope.selectedIngredient]++;
        }else {
      $scope.selectedIngredientResults[$scope.selectedIngredient] = 1;
        }
         console.log('$scope.selectedIngredientResults', $scope.selectedIngredientResults ); 
        }
    }

}

Answer 1

** 我花了一些时间来学习这些新方法，并从中获得一些灵感并通过另一种方式解决，非常感谢你们**

myApp.controller('addIngredientCtrl', function($scope) {
$scope.selectedIngredient = [];

$scope.addIngredient = function(selectedElement) {
var elementIndex = $scope.selectedIngredient.indexOf(selectedElement);
if(elementIndex === -1) {
  selectedElement['customerCartQuantity'] = 1;
  $scope.selectedIngredient.push(selectedElement);
} else {
  $scope.changeIngredientQuantity($scope.selectedIngredient[elementIndex],   1);
 }
 }

$scope.changeIngredientQuantity = function(selectedElement, value) {
var elementIndex = $scope.selectedIngredient.indexOf(selectedElement);
$scope.selectedIngredient[elementIndex].customerCartQuantity += value; 
if($scope.selectedIngredient[elementIndex].customerCartQuantity == 0) {
  $scope.selectedIngredient.splice(elementIndex, 1);
}

} });

Answer 2

我想这已经得到了回答，但这里是如何在一次减少中做到这一点：

$scope.selectedIngredientResults = $scope.selectedIngredient.reduce(function (result, item) {
    var foundIndex = -1;
    var found = result.some(function (alreadyCounted, i) {
        if (alreadyCounted.object.ingredient_id === item.ingredient_id) {
            foundIndex = i;
            return true;
        }
        return false;
    });
    if (found && foundIndex !== -1) result[foundIndex].count += 1;
    else result.push({object: item, count: 1});
    return result;
}, []);

Answer 3

首先您需要通过您的密钥应用 group by。然后从分组中提取结果。这是您需要的转换函数。

function transform(items) {
    items = items.reduce(function (memo, val) {
        var key = val['ingredient_id'];
        if (!memo[key]) {
            memo[key] = [];
        }
        memo[key].push(val);

        return memo;
    }, {});

    var result = [];
    for (var k in items) {
        var groups = items[k];
        result.push({ 'object': groups[0], 'count': groups.length });
    }

    return result;
}

Answer 4

function getIngredientResults (ingredients) {
  var source = [].slice.call(ingredients)
  var result = []

  while (source.length > 0) {
    // Move first item from source.
    var current = source.shift()

    // Find indexes of duplicate entries.
    var duplicateIndexes = source.reduce(function (carry, item, index) {
      if (item.ingredient_id === current.ingredient_id) {
        carry.push(index)
      }

      return carry
    }, [])

    // Remove duplicates from source.
    duplicateIndexes.forEach(function (index) {
      source.splice(index, 1)
    })

    // Add data to result
    result.push({
      ingredient: current,
      count: duplicateIndexes.length + 1
    })
  }

  return result
}