Angular Interview Practice

What is the difference between JIT and AOT compilation?

1. JIT is more secure than AOT

2. AOT is faster as it compiles at build time

3. JIT compiles at build time while AOT compiles at runtime

4. Both methods are identical in performance

The correct answer is: AOT is faster as it compiles at build time

The distinction between JIT (Just-In-Time) compilation and AOT (Ahead-Of-Time) compilation is critical for understanding Angular's performance and loading efficiency. AOT compilation is indeed faster because it translates your application into efficient JavaScript code during the build process, prior to deployment. This means that when the application is served to the client, the browser does not have to perform the compilation; it merely needs to interpret the precompiled code, which leads to quicker rendering and improved performance. Moreover, AOT can also catch errors during the build phase rather than at runtime, reducing the risk of runtime errors that can negatively impact user experience. The pre-compiled code also reduces the payload size sent to the client because the templates are compiled and included in the initial bundles sent by the server. In contrast, JIT compilation occurs at runtime, meaning the compilation happens in the browser, which can lead to longer loading times and a potentially slower performance due to the additional overhead associated with compiling the code on the client's side. Therefore, the correct answer highlights that AOT provides significant performance advantages by compiling at build time compared to JIT.