What is the difference between JIT and AOT in Angular ? 009

 What is the difference between JIT and AOT in Angular ?

In Angular, both Just-in-Time (JIT) and Ahead-of-Time (AOT) compilation play crucial roles in the development and deployment process, but they differ in several key aspects:

When Compilation Occurs:

• JIT: Compilation happens at runtime within the browser when the application first loads.

• AOT: Compilation happens during the build process before the application is deployed.

Performance and Bundle Size:

• JIT: Generally has slower initial load times due to runtime compilation. The browser needs to download and compile the code before running it. However, bundle size typically remains smaller since only the necessary code is downloaded to the browser.

• AOT: Offers faster initial load times because the code is already compiled and ready to run. However, it often results in larger bundle sizes since the entire application is pre-compiled, even if not all features are used immediately.

Development Experience:

• JIT: Provides faster development iteration because changes are immediately reflected in the browser without rebuilding the entire application.

• AOT: Requires rebuilding the application after every change, potentially slowing down development cycles. However, it offers better static error checking and tooling support.

Deployment and Environment Flexibility:

• JIT: Requires a JavaScript interpreter (like V8) to be available on the client side, limiting deployment flexibility.

• AOT: Can be deployed to platforms without a JavaScript interpreter since the code is already compiled into native JavaScript.

Other Considerations:

• SEO: AOT generally provides better search engine optimization (SEO) because crawlers can readily access and understand the pre-compiled code.

• Security: AOT can offer potential security benefits by making it harder to tamper with the code compared to JIT.

Choosing between JIT and AOT:

The best choice depends on your project's specific needs and priorities:

• JIT: Ideal for development, prototyping, and scenarios where quick iteration and flexibility are critical.

• AOT: Recommended for production deployments to gain performance advantages, better SEO, and potential security benefits.

Current Status:

While JIT was the default setting in earlier versions of Angular, AOT became the default with Angular 9 and is strongly recommended for most production scenarios.

I hope this comprehensive explanation clarifies the key differences and helps you choose the right compilation approach for your Angular project!