# Nullish Coalescing

The ?? operator, which uses a fallback only when its left value is null or undefined.

## What is **Nullish Coalescing** in JavaScript?

**Nullish Coalescing** — The ?? operator, which uses a fallback only when its left value is null or undefined.

```javascript
const nickname = null;
const displayName = nickname ?? "Guest";
```

Level: Apprentice · [More JavaScript terms at this level](https://www.ask-codey.com/glossary/subjects/javascript/apprentice)

Updated: September 27, 2026

Source: https://www.ask-codey.com/glossary/nullish-coalescing