find(), findIndex(), findLast()

Syntax

arr.find(item => condition)
arr.findIndex(item => condition)

Examples

const users = [
  { id: 1, name: "Alice" },
  { id: 2, name: "Bob" },
  { id: 3, name: "Charlie" }
];

const user = users.find(u => u.id === 2);
console.log(user); // { id: 2, name: "Bob" }

const notFound = users.find(u => u.id === 99);
console.log(notFound); // undefined

const numbers = [4, 9, 16, 25, 36];
const index = numbers.findIndex(n => n > 15);
console.log(index); // 2 (the index of 16)

const notFoundIndex = numbers.findIndex(n => n > 100);
console.log(notFoundIndex); // -1

const numbers = [1, 5, 8, 5, 2];

console.log(numbers.findLast(n => n === 5));      // 5 (the last matching value)
console.log(numbers.findLastIndex(n => n === 5)); // 3 (its index)

Best practices

• Use find() instead of filter()[0] when you only need the first match - it stops searching as soon as it finds one, which is more efficient
• Use findIndex() when you need the position for a subsequent operation like splice() or array update
• Prefer find()/findIndex() over indexOf() when searching by object property rather than exact primitive value
• Remember find() returns undefined (not -1) when nothing matches - check with a truthy check or === undefined, not === -1

At a glance

Purpose

Application logic and interaction

File extension

.js · .mjs

Runs in

Browsers and JavaScript runtimes

Usually used with

HTML, CSS and Web APIs

Specifications & further reading

• ECMAScript specification

Related JavaScript documentation