How to check whether a Storage item is set?

Question

How can I check if an item is set in localStorage? Currently I am using

if (!(localStorage.getItem("infiniteScrollEnabled") == true || localStorage.getItem("infiniteScrollEnabled") == false)) {     // init variable/set default variable for item     localStorage.setItem("infiniteScrollEnabled", true); } 

Answer 1

The getItem method in the WebStorage specification, explicitly returns null if the item does not exist:

... If the given key does not exist in the list associated with the object then this method must return null. ...

So, you can:

if (localStorage.getItem("infiniteScrollEnabled") === null) {   //... } 

See this related question:

• Storing Objects in HTML5 localStorage

Answer 2

You can use hasOwnProperty method to check this

> localStorage.setItem('foo', 123) undefined > localStorage.hasOwnProperty('foo') true > localStorage.hasOwnProperty('bar') false 

Works in current versions of Chrome(Mac), Firefox(Mac) and Safari.