Build hello_world.c using
emcc hello_world.c -Os -s WASM=1 -s SIDE_MODULE=1 -o hello_world.wasm
(make sure to use latest Emscripten incoming). That creates a
WebAssembly dynamic libraryhello_world.wasm. You can then run
hello_world.html in your browser, which loads and uses it.
More details: https://github.com/kripken/emscripten/wiki/WebAssembly-Standalone
| int doubler(int x) { | |
| return 2 * x; | |
| } |
| <html> | |
| <head> | |
| <script> | |
| // Check for wasm support. | |
| if (!('WebAssembly' in window)) { | |
| alert('you need a browser with wasm support enabled :('); | |
| } | |
| // Loads a WebAssembly dynamic library, returns a promise. | |
| // imports is an optional imports object | |
| function loadWebAssembly(filename, imports) { | |
| // Fetch the file and compile it | |
| return fetch(filename) | |
| .then(response => response.arrayBuffer()) | |
| .then(buffer => WebAssembly.compile(buffer)) | |
| .then(module => { | |
| // Create the imports for the module, including the | |
| // standard dynamic library imports | |
| imports = imports || {}; | |
| imports.env = imports.env || {}; | |
| imports.env.memoryBase = imports.env.memoryBase || 0; | |
| imports.env.tableBase = imports.env.tableBase || 0; | |
| if (!imports.env.memory) { | |
| imports.env.memory = new WebAssembly.Memory({ initial: 256 }); | |
| } | |
| if (!imports.env.table) { | |
| imports.env.table = new WebAssembly.Table({ initial: 0, element: 'anyfunc' }); | |
| } | |
| // Create the instance. | |
| return new WebAssembly.Instance(module, imports); | |
| }); | |
| } | |
| // Main part of this example, loads the module and uses it. | |
| loadWebAssembly('hello_world.wasm') | |
| .then(instance => { | |
| var exports = instance.exports; // the exports of that instance | |
| var doubler = exports._doubler; // the "doubler" function (note "_" prefix) | |
| // now we are ready, set up the button so the user can run the code | |
| var button = document.getElementById('run'); | |
| button.value = 'Call a method in the WebAssembly module'; | |
| button.addEventListener('click', function() { | |
| var input = 21; | |
| alert(input + ' doubled is ' + doubler(input)); | |
| }, false); | |
| } | |
| ); | |
| </script> | |
| </head> | |
| <body> | |
| <input type="button" id="run" value="(waiting for WebAssembly)"/> | |
| </body> | |
| </html> |