Front-end Frameworks

SpiderMonkey – JavaScript and WebAssembly Engine, used in Firefox, Servo and more

SpiderMonkey is the JavaScript and WebAssembly implementation library of the Mozilla Firefox web browser. The implementation behaviour is defined by the ECMAScript and WebAssembly specifications.

SpiderMonkey is intended to be embedded in other applications that provide host environments for JavaScript.

This is free and open source software.

Features include:

  • Interpreter – the bytecode generated by the parser may be executed by an interpreter written in C++ that manipulates objects in the GC heap and invokes native code of the host (eg. web browser)
  • JIT compiler – to speed up execution of bytecode, SpiderMonkey uses a series of Just-In-Time (JIT) compilers to generate specialized machine code (eg. x86, ARM, etc) tailored to the JavaScript that is run and the data that is processed. The WarpMonkey JIT replaces the former IonMonkey engine and is the highest level of optimization for the most frequently run scripts. It’s able to inline other scripts and specialize code based on the data and arguments being processed.
  • Garbage collector – elements of this heap have a base C++ type of gc::Cell. Each round of garbage collection will free up any Cell that is not referenced by a root or another live Cell in turn.
  • Implements the ECMA-262 specification (ECMAScript).
  • WebAssembly – in addition to JavaScript, the engine is also able to execute WebAssembly (WASM) sources.

Support: Code Repository
Developer: Mozilla Foundation
License: Mozilla Public License v2.0

SpiderMonkey is written in C++, Rust and JavaScript. Learn C++ with our recommended free books and free tutorials. Learn Rust with our recommended free books and free tutorials. Learn JavaScript with our recommended free books and free tutorials.

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