Implementing Iterator.range in SpiderMonkey

Serah Nderi shares her experience implementing the TC39 Range Proposal in the SpiderMonkey JavaScript engine. Iterator.range allows generating a sequence of numbers within a specified range, similar to Python’s range. Initially implemented with a generator-based approach, it was later optimized to a slot-based approach resulting in a 66.7% performance improvement. Challenges included handling Infinity checks and floating-point precision errors. The proposal is currently at stage 1 and built in Nightly only, disabled by default until it advances to further stages.