Storage.length

The length read-only property of the Storage interface returns an integer representing the number of data items stored in the Storage object.

Syntax

JavaScript
var aLength = storage.length;

Return value

An integer

Example

The following function adds three data items to the local storage for the current domain, then returns the number of items in the storage:

JavaScript
function populateStorage() {
  localStorage.setItem('bgcolor', 'yellow');
  localStorage.setItem('font', 'Helvetica');
  localStorage.setItem('image', 'cats.png');

  localStorage.length; // should return 3
}

Note: For a real world example, see our Web Storage Demo.

Specifications

Specification Status Comment
Web Storage
The definition of 'length' in that specification.
Recommendation  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
localStorage 4 3.5 8 10.50 4
sessionStorage 5 2 8 10.50 4
Feature Android Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support 2.1 ? 8 11 iOS 3.2

All browsers have varying capacity levels for both localStorage and sessionStorage. Here is a detailed rundown of all the storage capacities for various browsers.

Note: since iOS 5.1, Safari Mobile stores localStorage data in the cache folder, which is subject to occasional clean up, at the behest of the OS, typically if space is short.

See also

Using the Web Storage API

License

© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/api/storage/length

API Property Read-only Reference Référence Storage Web Storage