The length read-only property of the Storage interface returns an integer representing the number of data items stored in the Storage object.
Syntax
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:
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 |
|---|---|---|
| WHATWG HTML Living Standard The definition of 'Storage.length' in that specification. |
Living Standard |
Browser compatibility
| Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
|---|---|---|---|---|---|---|
| localStorage | 4 | (Yes) | 3.5 | 8 | 10.50 | 4 |
| sessionStorage | 5 | ? | 2 | 8 | 10.50 | 4 |
| Feature | Android | Edge | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|
| Basic support | 2.1 | (Yes) | ? | 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.