NonNull<T>
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 number value

Example Rust Usage

 

# #![allow(unused_variables)]
#fn main() {
use std::ptr;
use std::ptr::NonNull;
use wasm_bindgen::prelude::*;

#[wasm_bindgen]
pub unsafe fn take_pointer_by_value(x: Option<NonNull<u8>>) {
    Box::from_raw(x.unwrap().as_ptr());
}

#[wasm_bindgen]
pub fn return_pointer() -> Option<NonNull<u8>> {
    Some(NonNull::from(Box::leak(Box::new(42))))
}

#}

Example JavaScript Usage

 
import {
  take_pointer_by_value,
  return_pointer,
} from './guide_supported_types_examples';
import { memory } from './guide_supported_types_examples_bg';

let ptr = return_pointer();
let buf = new Uint8Array(memory.buffer);
let value = buf[ptr];
console.log(`The byte at the ${ptr} address is ${value}`);

take_pointer_by_value(ptr);