Searching & Sorting Arrays

Finding items

find returns the first match, some and every return booleans and includes checks for a value.

const users = [{ id: 1, age: 17 }, { id: 2, age: 30 }];
users.find(u => u.age > 18);      // { id: 2, age: 30 }
users.some(u => u.age < 18);      // true
users.every(u => u.age > 10);     // true
[1, 2, 3].includes(2);            // true

Sorting

sort() compares as strings by default. Always pass a comparator for numbers, and copy first with toSorted or a spread.

[10, 9, 1].sort();                 // [1, 10, 9]  (string order!)
[10, 9, 1].sort((a, b) => a - b);  // [1, 9, 10]
const sorted = [...nums].sort((a, b) => a - b); // keeps nums intact

Quick check

Quick check: Why does [10, 9, 1].sort() give [1, 10, 9]?

• It compares items as strings by default
• Sorting is random
• Numbers cannot be sorted
• It sorts by length