LocalStorage in TypeScript

What is LocalStorage?

LocalStorage is a web API provided by browsers that allows developers to store key-value pairs in its memory. This storage is isolated to the domain of the website, which means that values can only be accessed by the same domain.

LocalStorage is a great way to store data that needs to persist across page refreshes or even when the user comes back to the website at a later time.

Why use TypeScript with LocalStorage?

TypeScript is a superset of JavaScript that adds type annotations and other features to help developers write more robust and maintainable code. When working with LocalStorage, it can be helpful to have a type-safe way of reading and writing values to storage.

By using TypeScript with LocalStorage, developers can ensure that the values being stored and retrieved are of the correct type, reducing the risk of runtime errors.

How to use LocalStorage with TypeScript

In TypeScript, we can use the window.localStorage object to interact with LocalStorage. Here's an example of how to set a value:

const value = {
  name: "John",
  age: 30,
};

localStorage.setItem("user", JSON.stringify(value));

In this example, we're serializing an object to JSON and storing it under the key user. Notice that we're using JSON.stringify to convert the object to a string before storing it.

To retrieve the value, we can use the getItem method:

const user = JSON.parse(localStorage.getItem("user") || "");

Here, we're using JSON.parse to convert the string back to an object. We're also using the nullish coalescing operator (||) to handle the case where the value doesn't exist in storage.

Conclusion

LocalStorage is a powerful tool for storing data in web applications. By using TypeScript with LocalStorage, developers can ensure that their code is more robust and maintainable.