This is an tutorial/introduction into implementing a TC39 proposal in the SpiderMonkey JavaScript engine. It will consist of learning the proposal Array Grouping, reading the proposals specification, and creating the implementation while adhering to the specification.

The implementation will be mostly written in Self-hosted JavaScript, with several lines written in C++.

This tutorial will give an introduction to:

• Reading the ECMA-262 language specification
• Implementing a TC39 proposal in SpiderMonkey
• Testing a proposal with the Test262 test suite

My name is Rolf Martin Glomsrud, i am a 4th year Master student at the University of Bergen. In 2021 i had a project where i implemented the proposal Array Grouping in SpiderMonkey. When doing that i got an introduction into implementing TC39 proposals, and wanted to share what i learnt throughout that process.

Humans are imperfect. If you find any errors, inaccuracies, or other issues. Please do not hesitate to create a Pull Request!