wasm-bindgen · alexcrichton · Jun 3, 2019 · May 19, 2019 · May 19, 2019 · Jun 1, 2019
diff --git a/Cargo.toml b/Cargo.toml
@@ -78,6 +78,7 @@ members = [
   "examples/wasm2js",
   "examples/webaudio",
   "examples/webgl",
+  "examples/websockets",
   "examples/without-a-bundler",
   "examples/without-a-bundler-no-modules",
   "tests/no-std",

diff --git a/azure-pipelines.yml b/azure-pipelines.yml
@@ -148,7 +148,7 @@ jobs:
       - script: mv _package.json package.json && npm install && rm package.json
         displayName: "run npm install"
       - script: |
-          for dir in `ls examples | grep -v README | grep -v asm.js | grep -v raytrace | grep -v without-a-bundler`; do
+          for dir in `ls examples | grep -v README | grep -v asm.js | grep -v raytrace | grep -v without-a-bundler | grep -v websockets`; do
             (cd examples/$dir &&
             ln -fs ../../node_modules . &&
             npm run build -- --output-path $BUILD_ARTIFACTSTAGINGDIRECTORY/exbuild/$dir) || exit 1;

diff --git a/examples/websockets/Cargo.toml b/examples/websockets/Cargo.toml
@@ -0,0 +1,19 @@
+[package]
+name = "websockets"
+version = "0.1.0"
+authors = ["The wasm-bindgen Developers"]
+edition = "2018"
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+wasm-bindgen = "0.2.45"
+
+[dependencies.web-sys]
+version = "0.3.22"
+features = [
+  "ErrorEvent",
+  "MessageEvent",
+  "WebSocket",
+]
diff --git a/examples/websockets/README.md b/examples/websockets/README.md
@@ -0,0 +1,23 @@
+# WebSockets Example
+
+[View documentation for this example online][dox] or [View compiled example
+online][compiled]
+
+[compiled]: https://rustwasm.github.io/wasm-bindgen/exbuild/websockets/
+[dox]: https://rustwasm.github.io/wasm-bindgen/examples/websockets.html
+
+You can build the example locally with:
+
+```
+$ wasm-pack build --target web
+```
+
+Then serve the statics and navigate to `host:port`
+
+```
+# static server from https://crates.io/crates/https
+http
+
+# or use python
+python -m SimpleHTTPServer
+```
diff --git a/examples/websockets/index.html b/examples/websockets/index.html
@@ -0,0 +1,10 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <meta charset="utf-8">
+    <title>WebSockets example</title>
+    <script type="module" src="index.js"></script>
+</head>
+<bodt>
+</bodt>
+</html>
diff --git a/examples/websockets/index.js b/examples/websockets/index.js
@@ -0,0 +1,5 @@
+import init from './pkg/websockets.js';
+
+window.addEventListener('load', async () => {
+    await init('./pkg/websockets_bg.wasm');
+});
diff --git a/examples/websockets/src/lib.rs b/examples/websockets/src/lib.rs
@@ -0,0 +1,52 @@
+use wasm_bindgen::prelude::*;
+use wasm_bindgen::JsCast;
+use web_sys::{ErrorEvent, MessageEvent, WebSocket};
+
+macro_rules! console_log {
+    ($($t:tt)*) => (log(&format_args!($($t)*).to_string()))
+}
+
+#[wasm_bindgen]
+extern "C" {
+    #[wasm_bindgen(js_namespace = console)]
+    fn log(s: &str);
+}
+
+#[wasm_bindgen(start)]
+pub fn start_websocket() -> Result<(), JsValue> {
+    // Connect to an echo server
+    let ws = WebSocket::new("wss://echo.websocket.org")?;
+
+    // create callback
+    let onmessage_callback = Closure::wrap(Box::new(move |e: MessageEvent| {
+        // handle message
+        let response = e
+            .data()
+            .as_string()
+            .expect("Can't convert received data to a string");
+        console_log!("message event, received data: {:?}", response);
+    }) as Box<dyn FnMut(MessageEvent)>);
+    // set message event handler on WebSocket
+    ws.set_onmessage(Some(onmessage_callback.as_ref().unchecked_ref()));
+    // forget the callback to keep it alive
+    onmessage_callback.forget();
+
+    let onerror_callback = Closure::wrap(Box::new(move |e: ErrorEvent| {
+        console_log!("error event: {:?}", e);
+    }) as Box<dyn FnMut(ErrorEvent)>);
+    ws.set_onerror(Some(onerror_callback.as_ref().unchecked_ref()));
+    onerror_callback.forget();
+
+    let cloned_ws = ws.clone();
+    let onopen_callback = Closure::wrap(Box::new(move |_| {
+        console_log!("socket opened");
+        match cloned_ws.send_with_str("ping") {
+            Ok(_) => console_log!("message successfully sent"),
+            Err(err) => console_log!("error sending message: {:?}", err),
+        }
+    }) as Box<dyn FnMut(JsValue)>);
+    ws.set_onopen(Some(onopen_callback.as_ref().unchecked_ref()));
+    onopen_callback.forget();
+
+    Ok(())
+}
diff --git a/guide/src/SUMMARY.md b/guide/src/SUMMARY.md
@@ -21,6 +21,7 @@
   - [web-sys: `canvas` Julia set](./examples/julia.md)
   - [web-sys: WebAudio](./examples/web-audio.md)
   - [web-sys: WebGL](./examples/webgl.md)
+  - [web-sys: WebSockets](./examples/websockets.md)
   - [web-sys: `requestAnimationFrame`](./examples/request-animation-frame.md)
   - [web-sys: A Simple Paint Program](./examples/paint.md)
   - [Parallel Raytracing](./examples/raytrace.md)

diff --git a/guide/src/examples/websockets.md b/guide/src/examples/websockets.md
@@ -0,0 +1,29 @@
+# WebSockets Example
+
+[View full source code][code] or [view the compiled example online][online]
+
+[online]: https://rustwasm.github.io/wasm-bindgen/exbuild/websockets/
+[code]: https://github.com/rustwasm/wasm-bindgen/tree/master/examples/websockets/
+
+This example connects to an echo server on `wss://echo.websocket.org`,
+sends a `ping` message, and receives the response.
+
+## `Cargo.toml`
+
+The `Cargo.toml` enables features necessary to create a `WebSocket` object and
+to access events such as `MessageEvent` or `ErrorEvent`.
+
+```toml
+{{#include ../../../examples/websockets/Cargo.toml}}
+```
+
+## `src/lib.rs`
+
+This code shows the basic steps required to work with a `WebSocket`.
+At first it opens the connection, then subscribes to events `onmessage`, `onerror`, `onopen`.
+After the socket is opened it sends a `ping` message, receives an echoed response
+and prints it to the browser console.
+
+```rust
+{{#include ../../../examples/websockets/src/lib.rs}}
+```