What is Resolve guard in Angular?

Resolve guard is a feature in Angular that allows you to ensure that certain data is available before a route is activated. It is often used to fetch data from a server before a page is displayed, ensuring that the page has the necessary data to render properly.

Resolve guard is a great tool for handling asynchronous operations, as it allows you to keep your components clean and focused on their specific responsibilities. By using resolve guard, you can handle data fetching and error handling in a single place, making your code easier to maintain and understand.

When a route with resolve guard is activated, Angular will run the resolve guard function before the route is displayed. This function can return a promise or an observable, which Angular will then wait for to resolve before completing the route activation process. If the promise is rejected or the observable emits an error, the route activation will be canceled, and the user will not be navigated to the page.

Resolve guard is often used in combination with Angular’s routing system to ensure that a page has the necessary data before it is displayed. This can be particularly useful when building applications with complex data dependencies or when working with slow or unreliable backend services.

Overall, resolve guard is a powerful feature in Angular that can help you manage your application’s data fetching and error handling in a clean and centralized way. By using resolve guard, you can ensure that your pages have the necessary data to render properly, improving the user experience and the overall reliability of your application.