`const T` and `mut 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)]
fn main() {
use std::ptr;
use wasm_bindgen::prelude::*;

#[wasm_bindgen]
pub fn take_pointer_by_value(x: *mut u8) {}

#[wasm_bindgen]
pub fn return_pointer() -> *mut u8 {
    ptr::null_mut()
}
}

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);