guide: Add working with pointers example to types section

examples/guide-supported-types-examples/pointers.js

@@ -0,0 +1,12 @@
+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);

examples/guide-supported-types-examples/src/lib.rs

@@ -11,3 +11,4 @@ pub mod char;
 pub mod bool;
 pub mod js_value;
 pub mod boxed_js_value_slice;
+pub mod pointers;

examples/guide-supported-types-examples/src/pointers.rs

@@ -0,0 +1,10 @@
+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()
+}

guide/src/reference/types.md

@@ -163,6 +163,18 @@ garbage-collected heap and the Wasm linear memory with `TextDecoder` and
 |:---:|:---:|:---:|:---:|:---:|:---:|:---:|
 | Yes | No | No | Yes | No | No | A JavaScript number value |
 
+### Example Rust Usage
+
+```rust
+{{#include ../../../examples/guide-supported-types-examples/src/pointers.rs}}
+```
+
+### Example JavaScript Usage
+
+```js
+{{#include ../../../examples/guide-supported-types-examples/pointers.js}}
+```
+
 ## `u8` `i8` `u16` `i16` `u64` `i64` `isize` `size`
 
 | `T` parameter | `&T` parameter | `&mut T` parameter | `T` return value | `Option<T>` parameter | `Option<T>` return value | JavaScript representation |