#javascript #intern #wasm-bindgen


Internal implementation details for the js-intern crate

2 releases

✓ Uses Rust 2018 edition

0.3.1 Jul 5, 2019
0.3.0 Jul 5, 2019

#72 in Caching

Used in 3 crates (2 directly)

MIT license

108 lines

A macro for interning JavaScript primitives.

Stores one copy of each distinct JavaScript primitive. For example, js_intern!("string") evaluates to a &JsValue but uses only one heap allocation and a one-time translation from the utf-8 Rust string to the utf-16 JavaScript string the first time the expression is evaluated. Furthermore, values are de-duplicated across the program. So, any time js_intern!(1.0) is used in the program, the same instance of the JavaScript number is used.

Supported types

  • &'static str Eg: js_intern!("str")
  • f64, f32 u8, u16, u32, i8, i16, i32 Eg: js_intern(1.0)
  • bool Eg: js_intern(true)


If you like this, you may like these other crates by Zac Burns (That3Percent)

  • js-object A macro for creating JavaScript objects
  • soa-vec A struct of arrays layout with a Vec of tuple API
  • second-stack A Rust memory allocator for large slices that don't escape the stack.


~27K SLoC