← Errors
A QuotaExceededError (DOMException) is thrown when a write to localStorage or sessionStorage would exceed the browser's storage limit, typically around 5 MB per origin. The error name varies slightly across browsers.
Why it happens
- •Storing large JSON objects or base64-encoded images in localStorage.
- •Accumulating many small items over time that together exceed the quota.
- •Multiple tabs or the same app over time filling up the storage.
Examples
JavaScript
Code that triggers the error
const bigData = "x".repeat(10 * 1024 * 1024); // 10 MB
localStorage.setItem("cache", bigData);Error output
DOMException: Failed to execute 'setItem' on 'Storage': Setting the value of 'cache' exceeded the quota.
How to fix it
Wrap localStorage.setItem() in a try/catch for QuotaExceededError. Prune old or large items before writing. For larger data, use IndexedDB which has no hard size limit. Consider a cache eviction strategy (LRU, TTL) to keep storage size bounded.
Fixed code
function safeSetItem(key, value) {
try {
localStorage.setItem(key, value);
} catch (e) {
if (e.name === "QuotaExceededError") {
localStorage.clear();
localStorage.setItem(key, value);
}
}
}Related errors
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