Angular Tutorial: JIT vs AOT

beginner
13 min

Angular Tutorial: JIT vs AOT

Welcome to this comprehensive guide on Angular! In this lesson, we'll delve into the concepts of Just-in-Time (JIT) and Ahead-of-Time (AOT) compilers, two essential tools in the Angular ecosystem. Let's get started! 🎯

Understanding Compilation in Angular

Before we dive into JIT and AOT, let's first understand what compilation means in Angular. When you write TypeScript code, it needs to be compiled into JavaScript to run in the browser. Angular provides two ways to perform this compilation:

  1. Just-in-Time (JIT): Compilation happens at runtime, during the execution of the application. This is the default mode for Angular applications.

  2. Ahead-of-Time (AOT): Compilation happens before runtime, during the build process.

JIT Compilation 💡

JIT compilation is the default mode for Angular applications. Here's a simple breakdown of how it works:

  1. Write your TypeScript code.
  2. Angular's JIT compiler translates the TypeScript code into JavaScript at runtime.
  3. The JavaScript code is executed by the browser, and the application runs.

Advantages of JIT

  • Flexibility: JIT allows you to make changes to the TypeScript code and see the results immediately without rebuilding the application.
  • Development Speed: Since the compilation happens at runtime, you can quickly iterate on your code during the development process.

Disadvantages of JIT

  • Performance: JIT compilation adds a slight overhead during runtime, which can affect the performance of your application.
  • Bundle Size: JIT-compiled applications tend to have larger bundle sizes, which can lead to slower load times.

AOT Compilation 📝

In contrast to JIT, AOT performs the compilation during the build process:

  1. Write your TypeScript code.
  2. Angular's AOT compiler translates the TypeScript code into optimized, pre-compiled JavaScript and TypeScript files.
  3. The pre-compiled files are served by the server and executed by the browser.

Advantages of AOT

  • Performance: AOT-compiled applications run faster because the compilation happens before runtime, eliminating the need for runtime compilation.
  • Bundle Size: AOT reduces the bundle size of your application, leading to faster load times.
  • Tree Shaking: AOT allows for tree shaking, a process that removes unused code from your application, further reducing the bundle size.

Disadvantages of AOT

  • Development Speed: Since AOT compiles the code before runtime, you need to rebuild the application to see changes, which can slow down your development process.
  • Complexity: AOT requires more setup and understanding of the build process compared to JIT.

Choosing Between JIT and AOT ✅

The choice between JIT and AOT depends on your specific needs:

  • If you prioritize development speed and flexibility, go for JIT.
  • If you prioritize performance and a smaller bundle size, go for AOT.

Practice Time 💡

Let's reinforce our understanding of JIT and AOT with a quiz:

Quick Quiz
Question 1 of 1

Which type of compilation performs the compilation during the build process?

Stay tuned for our next lesson, where we'll dive deeper into setting up and using AOT in your Angular applications! 🚀