Web applications are increasingly relying on the client side for operations and this has brought to light the storage options available on the client side. While cookies have been around for a long time, modern browsers offer more options for saving data on the client side – one of them being Session Storage. Session storage as provided by the Web Storage API, is a simple key-value store that is limited to the scope of the page session. It allows us to store sizable amounts of data without impacting website performance. However, dealing with session storage can be tricky and it often involves checking if a particular object or value exists, specifically when dealing with authorization objects.
Consider a scenario where an authorization object is stored in session storage after a user logs into a web application. We might need to check if this authorization object exists in session storage, as it would indicate whether a user is authenticated or not. Let’s discuss how we can achieve this using JavaScript.
Using the getItem Method
let authObject = sessionStorage.getItem('auth');
if (authObject !== null) {
console.log('User is authenticated');
} else {
console.log('User is not authenticated');
}
The getItem method is a part of the Storage interface and can be used with sessionStorage. It returns the value corresponding to the key that we pass in as an argument. If the key doesn’t exist, it returns null. This JavaScript code first retrieves the ‘auth’ object from session storage and then checks if it’s null or not. If the object is not null, it implies that the user is authenticated. Else, the user is not authenticated.
Using the in Operator
if ('auth' in sessionStorage) {
console.log('User is authenticated');
} else {
console.log('User is not authenticated');
}
The JavaScript in operator can be used to check if a specific property exists in an object. In this example, the in operator checks if the ‘auth’ property exists in the sessionStorage object. If it does, the user is authenticated, or else, not authenticated.
Working with session storage is a good alternativeto cookies because of its eased functionality and enhanced storage capacity. You can store standard strings, numbers, arrays or even complex objects in session storage. While using session storage, be aware of the privacy implications as the data stored is accessible by all scripts running on your page. Being a client-side store, it is also susceptible to similar security issues as other client-side storage mechanisms. So, use it wisely and responsibly.
