Here are the top Angular interview questions to prepare for your next role.
1️⃣ In Angular, what is the primary distinction between an Attribute Directive and a Structural Directive?
- A) Structural directives alter the DOM layout by adding or removing elements.
- B) Attribute directives are required to inject services into a component class.
- C) Attribute directives are used solely for handling HTTP requests and responses.
- D) Structural directives only modify the appearance or behavior of an existing element.
2️⃣ What distinguishes Angular's Ahead-of-Time (AOT) compilation from Just-in-Time (JIT) compilation?
- A) AOT is used only for development builds; JIT is used strictly for production.
- B) AOT compiles TypeScript to JavaScript; JIT only compiles HTML templates.
- C) AOT compiles templates during the build phase; JIT compiles them in the browser.
- D) AOT requires a server-side environment; JIT runs entirely offline.
3️⃣ What is the primary purpose of a Pure Pipe in Angular?
- A) To trigger change detection on every single mouse movement or event.
- B) To transform data in the template only when the input reference changes.
- C) To asynchronously fetch data from an API and update the view continuously.
- D) To directly modify the original data source within the component class.
4️⃣ How does the 'OnPush' Change Detection Strategy differ from the 'Default' strategy?
- A) It triggers change detection immediately after every single asynchronous browser event.
- B) It completely disables change detection for the component and its children permanently.
- C) It triggers change detection only when input references change, an event occurs, or an async pipe emits.
- D) It forces the component to update only when the parent component explicitly calls a refresh method.
5️⃣ In Angular 17+, how does the @defer block optimize application performance?
- A) It forces the enclosed template to render asynchronously in a Web Worker.
- B) It lazy-loads the enclosed template content and its dependencies based on a trigger.
- C) It pauses the change detection cycle for the enclosed elements to save memory.
- D) It delays the execution of the component's constructor until the view is ready.