Boxed Number Slices: Box<[u8]>, Box<[i8]>, Box<[u16]>, Box<[i16]>, Box<[u32]>, Box<[i32]>, Box<[u64]>, Box<[i64]>, Box<[f32]>, Box<[f64]>, Box<[MaybeUninit<u8>]>, Box<[MaybeUninit<i8>]>, Box<[MaybeUninit<u16>]>, Box<[MaybeUninit<i16>]>, Box<[MaybeUninit<u32>]>, Box<[MaybeUninit<i32>]>, Box<[MaybeUninit<u64>]>, Box<[MaybeUninit<i64>]>, Box<[MaybeUninit<f32>]>, and Box<[MaybeUninit<f64>]>
T parameter | &T parameter | &mut T parameter | T return value | Option<T> parameter | Option<T> return value | JavaScript representation |
|---|---|---|---|---|---|---|
| Yes | No | No | Yes | Yes | Yes | A JavaScript TypedArray of the appropriate type (Int32Array, Uint8Array, etc...) |
Note: The contents of the slice are copied into a JavaScript
TypedArrayfrom the Wasm linear memory when returning a boxed slice to JavaScript, and vice versa when receiving a JavaScriptTypedArrayas a boxed slice in Rust.
Note: Numeric
MaybeUninit<T>can always be assumed to be initialized upon transmission from Rust to JS and vice-versa. However, uninitialized values coming from Rust might contain unspecified values.
Example Rust Usage
#![allow(unused)] fn main() { use wasm_bindgen::prelude::*; #[wasm_bindgen] pub fn take_boxed_number_slice_by_value(x: Box<[f64]>) {} #[wasm_bindgen] pub fn return_boxed_number_slice() -> Box<[u32]> { (0..42).collect::<Vec<u32>>().into_boxed_slice() } #[wasm_bindgen] pub fn take_option_boxed_number_slice(x: Option<Box<[u8]>>) {} #[wasm_bindgen] pub fn return_option_boxed_number_slice() -> Option<Box<[i32]>> { None } }
Example JavaScript Usage
import {
take_boxed_number_slice_by_value,
return_boxed_number_slice,
take_option_boxed_number_slice,
return_option_boxed_number_slice,
} from './guide_supported_types_examples';
take_boxed_number_slice_by_value(new Uint8Array(100));
let x = return_boxed_number_slice();
console.log(x instanceof Uint32Array); // true
take_option_boxed_number_slice(null);
take_option_boxed_number_slice(undefined);
take_option_boxed_number_slice(new Int16Array(256));
let y = return_option_boxed_number_slice();
if (y == null) {
// ...
} else {
console.log(x instanceof Int32Array); // true
}