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JS Engine Architecture - JS Runtime Environment - Event Loop


JavaScript (JS) is a high-level programming language that is commonly used for web development, both on the client-side and the server-side. The JS engine is the component that interprets and executes JavaScript code. The engine converts the JavaScript code into low-level machine code that the computer can understand and execute.


JS engine architecture can vary depending on the implementation, but generally, it consists of two main components:

  1. Memory Heap: This is where memory allocation takes place, and objects are stored.
  2. Call Stack: This is where the execution context is stored. The execution context is a data structure that contains information about the current state of the program, including the values of variables and the position in the code.

In addition to these two components, the JS engine also includes various other features such as:

  1. Parser: This component is responsible for parsing the JavaScript code and creating an abstract syntax tree (AST). The AST is a data structure that represents the program's structure and is used by the engine to execute the code.
  2. Garbage Collector: This is responsible for freeing up memory that is no longer being used by the program. It does this by identifying objects that are no longer referenced and deallocating their memory.
  3. Optimizer: This component is responsible for optimizing the code to improve its performance. It does this by analyzing the code and making changes to the way it is executed to make it run faster.


The JS engine is part of the larger JS runtime environment, which includes other components such as the Web API, event loop, and callback queue. The Web API provides interfaces for interacting with the browser or environment in which the code is running. The event loop and callback queue are responsible for managing asynchronous code execution.


Overall, the JS engine is a critical component of the JS runtime environment and is responsible for executing the JavaScript code efficiently and accurately.



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