[javascript] Javascript ES6/ES5 find in array and change

I have an array of objects. I want to find by some field, and then to change it:

var item = {...}
var items = [{id:2}, {id:2}, {id:2}];

var foundItem = items.find(x => x.id == item.id);
foundItem = item;

I want it to change the original object. How? (I dont care if it will be in lodash too)

An other approach is to use splice.

The splice() method changes the contents of an array by removing or replacing existing elements and/or adding new elements in place.

N.B : In case you're working with reactive frameworks, it will update the "view", your array "knowing" you've updated it.

Answer :

var item = {...}
var items = [{id:2}, {id:2}, {id:2}];

let foundIndex = items.findIndex(element => element.id === item.id)
items.splice(foundIndex, 1, item)

And in case you want to only change a value of an item, you can use find function :

// Retrieve item and assign ref to updatedItem
let updatedItem = items.find((element) => { return element.id === item.id })

// Modify object property
updatedItem.aProp = ds.aProp

Given a changed object and an array:

const item = {...}
let items = [{id:2}, {id:3}, {id:4}];

Update the array with the new object by iterating over the array:

items = items.map(x => (x.id === item.id) ? item : x)

worked for me

let returnPayments = [ ...this.payments ];

returnPayments[this.payments.findIndex(x => x.id == this.payment.id)] = this.payment;

One-liner using spread operator.

 const updatedData = originalData.map(x => (x.id === id ? { ...x, updatedField: 1 } : x));

Whereas most of the existing answers are great, I would like to include an answer using a traditional for loop, which should also be considered here. The OP requests an answer which is ES5/ES6 compatible, and the traditional for loop applies :)

The problem with using array functions in this scenario, is that they don't mutate objects, but in this case, mutation is a requirement. The performance gain of using a traditional for loop is just a (huge) bonus.

const findThis = 2;
const items = [{id:1, ...}, {id:2, ...}, {id:3, ...}];

for (let i = 0, l = items.length; i < l; ++i) {
  if (items[i].id === findThis) {
    items[i].iAmChanged = true;
    break;
  }
}

Although I am a great fan of array functions, don't let them be the only tool in your toolbox. If the purpose is mutating the array, they are not the best fit.

My best approach is:

var item = {...}
var items = [{id:2}, {id:2}, {id:2}];

items[items.findIndex(el => el.id === item.id)] = item;

Reference for findIndex

And in case you don't want to replace with new object, but instead to copy the fields of item, you can use Object.assign:

Object.assign(items[items.findIndex(el => el.id === item.id)], item)

as an alternative with .map():

Object.assign(items, items.map(el => el.id === item.id? item : el))

Functional approach:

Don't modify the array, use a new one, so you don't generate side effects

const updatedItems = items.map(el => el.id === item.id ? item : el)

May be use Filter.

const list = [{id:0}, {id:1}, {id:2}];
let listCopy = [...list];
let filteredDataSource = listCopy.filter((item) => {
       if (item.id === 1) {
           item.id = 12345;
        }

        return item;
    });
console.log(filteredDataSource);

Array [Object { id: 0 }, Object { id: 12345 }, Object { id: 2 }]