how to add an element of array to another object and count number

Question

Firstly, I have an array with object element like below:

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

secondly , I have a new object :

$scope.selectedIngredientResults = {};

Now I wanna achieve one function in javascript like this:

count each object element of array and put them into a new object and store each

count

$scope.selectedIngredientResults = [

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

];

[![here is new object result, this is what I want,

I was trying using

$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 ); 
        }
    }

}

How are you identifying two objects as being the same (is it actually the same object, or just the same properties)? — Paddy
– Paddy, Commented Sep 5, 2016 at 12:57
@ Paddy each object has ingredient_id and using obj.hasOwnProperty to identify 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; } — Agnes
– Agnes, Commented Sep 5, 2016 at 13:06
I know it's not the answer, but for this kind of task lodash is great lodash.com — Daniel Apt
– Daniel Apt, Commented Sep 5, 2016 at 13:44
If this is an AngularJS question, please tag it as so, as it may add different considerations than with vanilla Javascript. — Boaz
– Boaz, Commented Sep 5, 2016 at 15:34

Sufian Saory · Accepted Answer · 2016-09-05 15:30:12Z

1

first you need to apply group by by your key. then extract the result from the grouping. here is a transform function what you would need.

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;
}

answered Sep 5, 2016 at 15:30

Sufian Saory

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5 Comments

Agnes Over a year ago

i am trying to understand your code, but i still can not understand what's going on here items = items.reduce(function (memo, val) { var key = val['ingredient_id']; if (!memo[key]) { memo[key] = []; } memo[key].push(val); return memo; }, {});

Sufian Saory Over a year ago

it's applying group by operation. just console.log(items) when reducing is done, you'll know what is been done for more abount reduce see(developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…). :)

Agnes Over a year ago

can u explain val['ingredient_id'] ?@Sufian Saory

Sufian Saory Over a year ago

val is the current object for the reducing iteration. val['ingredient_id'] is the value of the ingredient_id which is the key for our group by operation. please see(w3schools.com/jsref/jsref_reduce.asp) with example of reduce.

Agnes Over a year ago

Thanks @Sufian Saory

Jon Koops · Accepted Answer · 2016-09-05 13:43:43Z

0

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
}

answered Sep 5, 2016 at 13:43

Jon Koops

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2 Comments

Agnes Over a year ago

sorry @Jon Koops it is my fault, i should tag it AngularJS, but still thank your help

Jon Koops Over a year ago

This is just a function, you can use it with AngularJS. AngularJS is still JavaScript...

Olli K · Accepted Answer · 2016-09-05 16:57:22Z

0

I guess this was already answered but here's how to do it in one reduce:

$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;
}, []);

answered Sep 5, 2016 at 16:57

Olli K

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Comments

Agnes · Accepted Answer · 2016-09-06 11:54:22Z

** I spend some time to learn these new methods above your guys answer and get some inspiration from these and worked it out by another way , Thank u so much guys **

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);
}

} });

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