CODEWITHSUNDEEP
javascriptarrays
Liga
Liga

Reputation: 3439

How to change the original array using filter?

I use filter to find all the items in a nested array. But then I would like to change the "quantity" of all the found items. The same item can be found in multiple categories and subcategories.

It would be nice if I could modify it like this, but it is not working...

let item_id = 681
let new_quantity = 10

categories.flatMap(category => category.subcategories.flatMap(subcategory => subcategory.items))
          .filter(item => item.id == item_id)
          .item.quantity = new_quantity

Here is my categories > subcategories > items array (I want to change quantity from 5 to 10 where item_id = 681)

[
    {
        id: 1,
        description: 'First category',
        subcategories: [
            {
                id: 1,
                description: 'First subcategory',
                items: [
                    {
                        id: 681,
                        description: 'House',
                        quantity: 5,
                    }
                ]
            }
        ]
    },

    {
        id: 2,
        description: 'Second category',
        subcategories: [
            {
                id: 1,
                description: 'First subcategory',
                items: [
                    {
                        id: 681,
                        description: 'House',
                        quantity: 5,
                    }
                ]
            }
        ]
    },
]

Upvotes: 0

Views: 2278

Answers (2)

Mischa
Mischa

Reputation: 1701

If the depth of the nested categories is variabel (e.g. you habe sub-sub-categories), then this might be helpful also:

let categories = [{id:1,description:"First category",subcategories:[{id:1,description:"First subcategory",items:[{id:681,description:"House",quantity:5}]}]},{id:2,description:"Second category",subcategories:[{id:1,description:"First subcategory",items:[{id:681,description:"House",quantity:5}]}]}];

let item_id = 681
let new_quantity = 10

function eachRecursive(obj, cb) {
    for (var k in obj) {
        cb(k, obj);
        if (typeof obj[k] == "object" && obj[k] !== null)
            eachRecursive(obj[k], cb);
    }
}

eachRecursive(categories, (key, obj) => {
  if(key === 'items') { 
    let itemIndex = obj[key].findIndex(item => item.id === item_id);
    obj[key][itemIndex].quantity = new_quantity; 
  }
});

console.log(categories);

Upvotes: 0

Vladimir Bogomolov
Vladimir Bogomolov

Reputation: 1794

Use map instead.

categories.flatMap(category => category.subcategories.flatMap(subcategory => subcategory.items))
   .map(item =>{
    if(item.id == item_id){
     item.quantity = new_quantity;
    }
   return item;
})

Upvotes: 1

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