src/examples/wasm: Show both methods supported

Adds another example showing the simple case of executing main, adds a README explaining how everything fits together and how to execute the compiled code in the browser. Include a minimal webserver for local testing.
2026-08-09 05:23:40 +00:00 · 2019-04-16 14:58:11 +01:00
parent a00a51e70e
commit 586023b45d
12 changed files with 244 additions and 25 deletions
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+
+<html>
+
+<head>
+	<meta charset="utf-8" />
+	<title>Go WebAssembly</title>
+	<meta name="viewport" content="width=device-width, initial-scale=1" />
+	<script src="wasm_exec.js" defer></script>
+	<script src="wasm.js" defer></script>
+</head>
+
+<body>
+	<h1>WebAssembly</h1>
+	<p>Add two numbers, using WebAssembly:</p>
+	<input type="number" id="a" value="2" /> + <input type="number" id="b" value="2" /> = <input type="number"
+		id="result" readonly />
+</body>
+
+</html>
@@ -0,0 +1,25 @@
+package main
+
+import (
+	"strconv"
+	"syscall/js"
+)
+
+func main() {
+}
+
+//go:export add
+func add(a, b int) int {
+	return a + b
+}
+
+//go:export update
+func update() {
+	document := js.Global().Get("document")
+	aStr := document.Call("getElementById", "a").Get("value").String()
+	bStr := document.Call("getElementById", "b").Get("value").String()
+	a, _ := strconv.Atoi(aStr)
+	b, _ := strconv.Atoi(bStr)
+	result := add(a, b)
+	document.Call("getElementById", "result").Set("value", result)
+}
@@ -0,0 +1,35 @@
+'use strict';
+
+const WASM_URL = 'wasm.wasm';
+
+var wasm;
+
+function updateResult() {
+  wasm.exports.update();
+}
+
+function init() {
+  document.querySelector('#a').oninput = updateResult;
+  document.querySelector('#b').oninput = updateResult;
+
+  const go = new Go();
+  if ('instantiateStreaming' in WebAssembly) {
+    WebAssembly.instantiateStreaming(fetch(WASM_URL), go.importObject).then(function (obj) {
+      wasm = obj.instance;
+      go.run(wasm);
+      updateResult();
+    })
+  } else {
+    fetch(WASM_URL).then(resp =>
+      resp.arrayBuffer()
+    ).then(bytes =>
+      WebAssembly.instantiate(bytes, go.importObject).then(function (obj) {
+        wasm = obj.instance;
+        go.run(wasm);
+        updateResult();
+      })
+    )
+  }
+}
+
+init();