🔧 What You Need To Know About JavaScript V8 Engine

When you hear the words “V8 Engine” you probably think of the popular design for automotive engines. They are well-known for their powerful and smooth performance across the board. The JavaScript V8 engine is no different. This powerful software is unrivalled when it comes to execution of Js code. Its high versatility makes it a perfect fit for a variety of applications. Here are the details.

What is it?

The V8 engine is a software whose primary role is to translate Js code into machine code (compilation). It was created by Google for the Chrome web browser to enhance the speed and overall performance. However, due to its unique and useful features it is nowadays used on multiple fronts. For instance, it is also used by Microsoft Edge and Node.js.

Older engines used to interpret JavaScript code directly and this had an impact on speed and efficiency. Therefore, Js couldn’t be used for applications that require faster execution times. V8 engine takes a hybrid approach that includes both interpretation (to bytecode) and compilation. This makes it very efficient. In addition, the engine supports WebAssembly hence allowing execution of code written in languages such as Rust and C++.

Key Features

• Just-In-Time (JIT) Compilation
This is a technique that ensures the code is compiled at
runtime when needed. Only the frequently used parts of the code are compiled thus promoting high-speed execution. This is done using the TurboFan compiler. Before the compilation, the Ignition Interpreter first does the translation into bytecode. This hybrid approach creates a fine balance between fast startup times and high-speed execution.

• Garbage Collection
It frees up unused memory thereby preventing memory leaks. This is done based on the generations i.e. it uses quick cleanup for short-lived objects (young generation) and a more optimized cleanup for long-lived objects (old generation). Since the garbage collection is done in small steps it doesn’t stop execution thus ensuring smooth performance.

• WebAssembly Support
The fact that it can run WebAssembly code alongside JavaScript allows near-native performance for web apps. The WebAssembly code can be compiled Ahead-Of-Time (AOT). The execution is even faster than JIT-compiled JavaScript. This allows for high-performance web apps like Figma and Photoshop Web.

• Hidden Classes and Inline Caching
Instead of dynamically assigning properties which tends to be slow, it creates hidden classes behind the scenes to structure objects efficiently. If a function accesses the same property multiple times V8 remembers its location through inline caching and avoids looking it up again. Reduced lookup time translates to faster access.

• Optimization and De-optimization
It employs various techniques to optimize the code and can also de-optimize it if need be. For example, if the applied assumptions turn out to be wrong it can roll back and use the slower generic version thus ensuring that execution still happens correctly.

Conclusion

The JavaScript V8 engine is one of the fastest and most efficient engines. It offers a robust platform that combines both compilation and interpretation to provide the best performance. The ability to execute WebAssembly code and to power both browsers & sever-side applications through Node.js makes it a versatile engine. In addition, it is open-source and has cross-platform compatibility hence making it widely accessible. For more detailed information checkout the documentation.