Compared to the existing box2d.js package: box2d-wasm aims to support Box2D v2.4.0+ and TypeScript.
The most important user-facing differences are:
| Criteria | box2d.js |
box2d-wasm |
|---|---|---|
| Box2D version compatibility | v2.3.1 | v2.4.1 (latest) |
| TypeScript declarations | No | Yes |
| Distributes UMD module | Yes | Yes |
| Distributes ES module | No | Yes |
| Distributes WebAssembly | Yes | Yes |
| Distributes asm.js | Yes | No |
| JS+WASM Size, kB | 467 | 537 |
| JS+WASM Size, kB (.gz) | 111 | 121 |
Summary: I dropped older practices (asm.js) and adopted newer practices (ES modules, TypeScript).
box2d-wasm is 9% bigger (but exports more+newer functionality).
The performance is likely to be identical (they're compiled with moreorless the same Emscripten flags).
The featureset is similar; box2d-wasm exports Box2D functionality via the same WebIDL bindings box2d.js used, but adds some updates for Box2D v2.4.1.
box2d-wasm additionally exposes some array properties and collision functions.
The invocation is similar; functionality is bound in the same way, so existing box2d.js examples and documentation should be broadly compatible with box2d-wasm (except for API differences specific to Box2D v2.4.1).
box2d-wasm provides a small number of helper functions for working with Emscripten types.
As for how it's developed, the differences from box2d.js are:
- Different build system, to support the newer cmake build system introduced in Box2D v2.4.0.
- Different approach to version controlling source code and build output
More detail at README.project-aims.md.