Nan Boxing

1. WebKit

   1 167 8,310 10.0 JavaScript

   Home of the WebKit project, the browser engine used by Safari, Mail, App Store and many other applications on macOS, iOS and Linux.

   

   v8 does not use NaN-boxes; instead they use the low bit to distinguish between a 31-bit small integer ("smi") or a pointer. Doubles are additionally sometimes stored inline ("double field unboxing") I'm not sure how this works exactly. Other times they are heap-allocated. I am not sure if there is a specialized double-allocator, I'd like to know.

   JavaScriptCore uses a tweaked NaN-box [1]: values are stored via a NaN box minus a constant, which avoids requiring a mask when chasing pointers. This makes pointers cheaper but floating point operations more expensive.

   SpiderMonkey and Hermes both use straight NaN-boxing to my knowledge.

   https://github.com/WebKit/WebKit/blob/ec6b5337e777f9b460ec6b...

2. Nutrient

   nutrient.io featured

   Nutrient - The #1 PDF SDK Library. Bad PDFs = bad UX. Slow load times, broken annotations, clunky UX frustrates users. Nutrient’s PDF SDKs gives seamless document experiences, fast rendering, annotations, real-time collaboration, 100+ features. Used by 10K+ devs, serving ~half a billion users worldwide. Explore the SDK for free.

   

3. Duktape

   2 10 5,989 6.4 JavaScript

   Duktape - embeddable Javascript engine with a focus on portability and compact footprint

   

4. rust

   3 2,783 101,153 10.0 Rust

   Empowering everyone to build reliable and efficient software.

   

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