装箱的数字切片：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>]> 和 Box<[MaybeUninit<f64>]>

注意： 当将装箱的切片返回给 JavaScript 时，切片的内容会从 Wasm 线性内存复制到 JavaScript TypedArray 中；反之，当在 Rust 中接收 JavaScript TypedArray 作为装箱的切片时，也会进行复制。

注意： 数值型的 MaybeUninit<T> 在从 Rust 传输到 JS 以及从 JS 传输到 Rust 时，始终可以假定为已初始化。 但是，来自 Rust 的未初始化的值可能包含未指定的值。

Rust 使用示例

#![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
}
}

JavaScript 使用示例

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
}