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JAVASCRIPT DATA / CHAPTER 02 / Learn / LESSON 11

find.

About 5–10 minutes

Tenth class. .find returns the first matching element, or undefined if none.

function findByCategory(items, category) { return items.find((item) => item.category === category); }

Looking up "rent" finds the object. A missing category → undefined (not [] and not an error). An empty array also returns undefined.

Common mistake: expecting [] instead of undefined; or using filter[0] without knowing the difference.

Your lesson

Given: items = [{ amount: 5, category: "food" }, { amount: 8, category: "rent" }]. Write findByCategory(items, category), using find to return the first matching object. Print the result for "rent": { amount: 8, category: "rent" }. For "travel" and for an empty array, the result is undefined.

find stops at the first match or yields undefined.

lesson_11.jsJAVASCRIPT

Loading the runtime… The first launch may take a little longer.

… 0/20000

STANDBY

budget-data.logIDLE

> waiting for arrays / objects…
> report: —
▌

Code Lab

DATA STANDBY

01find or findByCategory

02finds rent

03missing is undefined

ConsoleWrite the code. Bring it online.

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