Java Reference
In-Depth Information
getting data
Retrieving data from local storage is just as straightforward as setting it. With the getItem()
method, you supply the key for which you want the value of:
var name = localStorage.getItem("userName");
This code uses the getItem() method to retrieve the value associated with the " userName " key and
assigns that value to the name variable. In the case of the example from the previous section, name
would contain " Paul ".
You can also use the key as localStorage is property if it is a valid identifier:
var name = localStorage.userName;
This code also gets the value of Paul and assigns it to the name variable.
A word of note: Keys are case‐sensitive. That may seem obvious if you are using object
.propertyName syntax, but the rule applies to setItem() and getItem() . For example:
localStorage.setItem("userName", "Paul");
var name = localStorage.getItem("UserName"); // null
This code set a key of userName with a value of Paul . It then tries to retrieve a value with the key of
UserName . Because of the uppercase U , UserName and userName are two different keys. We haven't
set a value with UserName , so getItem() returns null .
removing data
Eventually, you will want to remove some data that you stored in local storage, and you can do that
with the removeItem() method. Simply provide the key you want to remove, and the key/value pair
will be deleted from local storage. For example:
localStorage.removeItem("userName");
This code deletes the userName/Paul key/value pair from local storage. If the key is a valid
JavaScript identifier, you can also use object.propertyName syntax to do the same thing, like so:
localStorage.userName = null;
Here, you assign the value of null to the userName key/property, thus removing the key/value pair
from local storage.
If your goal is to remove all keys and values from local storage, you can use the clear() method,
like this:
localStorage.clear(); // no more key/value pairs
storing data as strings
It's important to note that web storage is a string‐only data store. This means that keys and their
values can only be strings. If you try to store some other type of value (like a number) or object, it is
 
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