The setItem() method of the Storage interface, when passed a key name and value, will add that key to the given Storage object, or update that key's value if it already exists.


storage.setItem(keyName, keyValue);


A DOMString containing the name of the key you want to create/update.
A DOMString containing the value you want to give the key you are creating/updating.

Return value



setItem() may throw an exception if the storage is full. Particularly, in Mobile Safari (since iOS 5) it always throws when the user enters private mode. (Safari sets the quota to 0 bytes in private mode, unlike other browsers, which allow storage in private mode using separate data containers.) Hence developers should make sure to always catch possible exceptions from setItem().


The following function creates three data items inside local storage.

function populateStorage() {
  localStorage.setItem('bgcolor', 'red');
  localStorage.setItem('font', 'Helvetica');
  localStorage.setItem('image', 'myCat.png');

Note: To see this used within a real world example, see our Web Storage Demo.


Specification Status Comment
HTML Living Standard
The definition of 'Storage.setItem' in that specification.
Living Standard

Browser compatibility

BCD tables only load in the browser

See also