How will you explain the concept of hierarchy? How many scopes can an application have?

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Each Angular application contains one root scope, but there can be several child scopes. The application may have multiple scopes because child controllers and some directives create new child scopes. When the new scope is formed or created, it is added as a child of the parent scope. As similar to DOM, scopes also create a hierarchical structure.

In AngularJS, the concept of hierarchy is related to the scope hierarchy. Each AngularJS application has a hierarchical structure of scopes that corresponds to the structure of the HTML elements in the document. The scope hierarchy is important for data binding and the propagation of changes.

In AngularJS, scopes are objects that refer to the model and act as a glue between the controller and the view. Scopes form a hierarchy based on the HTML structure, where each controller creates its own scope. This hierarchy allows for the inheritance of properties and methods from parent scopes to child scopes.

Here’s a brief explanation of the scope hierarchy:

  1. Root Scope: The $rootScope is the top-level scope in an AngularJS application. It’s a parent scope for all other scopes in the application.
  2. Controller Scopes: Each controller in your application creates its own scope, which is a child scope of the $rootScope. If a controller is nested within another controller, it forms a child scope, creating a hierarchical structure.
  3. Directive Scopes: Directives like ng-repeat or ng-if can create their own scopes as well. These scopes are also part of the hierarchy and inherit from their parent scope.

In summary, the scope hierarchy in AngularJS follows the structure of HTML elements, creating a tree-like arrangement. Parent scopes can have child scopes, and data and functions are inherited from parent to child scopes.

As for the number of scopes an application can have, technically, there is no strict limit. Each controller, directive, or isolated scope creates its own scope. The number of scopes depends on the structure and complexity of your application. However, it’s essential to manage scopes efficiently to avoid performance issues, as excessive scopes can impact the digest cycle and lead to decreased performance