Lifecycle hooks in Angular

Lifecycle hooks are a special functionality in Angular that allow us to “hook into” and run code at a specific lifecycle event of a component or directive.

Angular manages components and directives for us? ?when it creates them, updates them, or destroys them. With lifecycle hooks, we can gain better control of our application.

https://www.c-sharpcorner.com/blogs/angular-lifecycle-hooks

Please refer 

https://www.c-sharpcorner.com/article/learn-about-angular-component-hook-life-cycle/