JavaScript › Browser Storage & Web APIs

How do you check available and used storage quota in a browser?

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Answer

Use the StorageManager API's navigator.storage.estimate(), which returns a Promise resolving to an object with usage and quota (both in bytes), covering localStorage, IndexedDB, Cache API, and other origin storage combined.

const { usage, quota } = await navigator.storage.estimate();
console.log(`Using ${usage} of ${quota} bytes`);

Real-world example Warning users before an offline-capable app runs out of storage space for cached data.

Common follow-ups: What is navigator.storage.persist() used for?

Memory Management & Garbage Collection