CODEWITHSUNDEEP
javascriptarraysecmascript-6filter
Rinael
Rinael

Reputation: 155

Filter id in an array of object based on an array of id's

I am trying to display Heart icon for the items that are added to the Wishlist. I am using local storage to save the items that are wishlisted. I have an array of id's such as wishlistIds = [123,425,212,512,516]. So I want to check if the id's in that array matches with the array of objects (which are the products). Product array of objects looks like this;

 items = [{id:123, productName:"Cheese", price: 15.99}, {id:599, productName: "Honey", price:21.99}]

I have been trying to use Array.filter method to achieve what I want, but couldn't make it work;

wishlistIds.filter(w => w.id === items.id)

The above code returns me all the ids inside the wishlistIds without filtering the id's inside the the items. What is the correct way to approach this problem?

Upvotes: 3

Views: 6501

Answers (2)

Phil
Phil

Reputation: 164795

Create a Set of item IDs and use that to filter the wishlist array

const wishlistIds = [123,425,212,512,516]
const items = [{id:123, productName:"Cheese", price: 15.99}, {id:599, productName: "Honey", price:21.99}]

const itemIds = new Set(items.map(({ id }) => id))

const filteredWishlist = wishlistIds.filter(id => itemIds.has(id))

console.log(filteredWishlist)

I'm using a Set here as Set.prototype.has() is O(1) time complexity as opposed to Array.prototype.includes() which is O(n).

See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set#performance

Upvotes: 3

Kinglish
Kinglish

Reputation: 23654

First filter the list, then map it to get just the ID

let wishlistIds = [123,425,212,512,516]
let items = [{id:123, productName:"Cheese", price: 15.99}, {id:599, productName: "Honey", price:21.99}]
let hearts = items.filter(w => wishlistIds.includes(w.id)).map(w => w.id)
console.log(hearts)

Upvotes: 2

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