Angular : Jit vs AOT compilation usage and benefits

Angular Compilers

Angular supports both Ahead-of-Time (AOT) compilation and Just-in-Time (JIT) compilation. Let's explore the differences between them:

Features AOT JIT
Compilation Timing:s AOT (Ahead-of-Time): Compilation occurs during the build process, before the application is deployed to the client's browser. This means that templates and components are compiled to JavaScript during the development or build phase. JIT (Just-in-Time): Compilation occurs in the client's browser at runtime. The Angular compiler is included in the application bundle, and it compiles templates and components on-the-fly as the application runs.
Performance: AOT: AOT compilation often results in better runtime performance. The generated code is optimized for the specific environment during the build process, and the browser only needs to download the pre-compiled JavaScript, reducing the time spent on compilation at runtime. JIT: Since JIT compilation happens at runtime, there is an additional overhead, and the browser needs to compile the templates and components before rendering them. This can result in a slower initial load time for the application.
Bundle Size: AOT: AOT compilation can lead to smaller bundle sizes. During AOT, the Angular compiler can eliminate parts of the framework that are not needed for the specific application, resulting in a more compact bundle. JIT: JIT includes the Angular compiler in the bundle, which adds to the overall size of the application.
Security: AOT: AOT can enhance security by detecting and preventing certain types of errors during the build process. It also reduces the risk of injection attacks, as the templates are already compiled. JIT: Since compilation happens in the browser, there is a theoretical risk of template injection attacks if proper precautions are not taken.

In summary, AOT compilation is often preferred for production environments due to its performance benefits, smaller bundle sizes, and enhanced security.

JIT compilation, on the other hand, might be more suitable during development for faster build times and easier debugging. Angular CLI provides commands for both AOT and JIT compilation, allowing developers to choose the appropriate mode based on their needs.