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Author: patrick96

native-image/wasm-javac/README.md

@@ -1,3 +1,47 @@
 # Compile `javac` to a Wasm Module
 
-TODO
+In this example, we'll compile the `javac` tool to Wasm modules that can then run on the commandline or the browser.
+
+## Prerequisites
+
+These examples require:
+
+1. An [Oracle GraalVM Early Access Build](https://github.com/graalvm/oracle-graalvm-ea-builds), version 25.0.0-.ea.15 or later.
+    For example, using SDKMAN!: `sdk install java 25.ea.15-graal`
+2. The [Binaryen toolchain](https://github.com/WebAssembly/binaryen) on the sytem path, version 119 or later
+    For example, using Homebrew: `brew install binaryen`
+
+
+## Run `javac` CLI
+
+1. Build the Wasm binary:
+    ```bash
+    mvn -Pnative package
+    ```
+    Uses the [Native Build Tools](https://graalvm.github.io/native-build-tools/latest/index.html) to run the `native-image` executable from Maven.
+    This will generate the Wasm file and its JavaScript wrapper in the `target` directory.
+
+2. Compile a Java file:
+    ```bash
+    node target/javac.js HelloWorld.java
+    ```
+    The resulting `HelloWorld.class` file is placed next to `HelloWorld.java`.
+    This requires Node.js 22 or later.
+
+## Run Web Demo
+
+1. Build the Wasm binary:
+    ```bash
+    mvn -Pjavacweb package
+    ```
+    This generates the Wasm and JS files into the `web` directory.
+
+2. Host Web Server:
+    ```bash
+    cd web
+    jwebserver
+    ```
+    This will serve the `web` directory locally on port `8000`.
+
+3. Navigate to http://localhost:8000 to compile Java programs in the browser:
+![](images/screenshot.png)