Merge 01826acc96 into 01c31ea804

ports/webassembly/README.md

@@ -88,6 +88,20 @@ MicroPython code execution will suspend the browser so be sure to atomize usage
 within this environment. Unfortunately interrupts have not been implemented for the
 browser.
 
+Running with WebWorkers on browsers
+-----------------
+To enable WebWorker support and receive messages outside of DOM, set `Module.webWorkerEventCallback` to a function that'll receive the events.
+
+```
+importScripts('micropython.js');
+// ...
+Module.webWorkerEventCallback = (event) => {
+  console.log(`Received an event from MicroPython!`);
+};
+```
+
+WebWorkers on the web gives more flexibility to developers when consuming the WASM module. Example cases where this is useful are: not blocking main thread, creating and disposing multiple instances on a single session, using multiple instances for different purposes separate from each other...
+
 Testing
 -------
 

ports/webassembly/library.js

@@ -27,7 +27,9 @@
 mergeInto(LibraryManager.library, {
     mp_js_write: function(ptr, len) {
         const buffer = HEAPU8.subarray(ptr, ptr + len)
-        if (ENVIRONMENT_IS_NODE) {
+        if (ENVIRONMENT_IS_WORKER && typeof Module.webWorkerEventCallback === 'function') {
+            Module.webWorkerEventCallback({detail: buffer});
+        } else if (ENVIRONMENT_IS_NODE) {
             process.stdout.write(buffer);
         } else {
             const printEvent = new CustomEvent('micropython-print', { detail: buffer });

ports/webassembly/wrapper.js

@@ -35,7 +35,7 @@ var mainProgram = function()
 
   MP_JS_EPOCH = Date.now();
 
-  if (typeof window === 'undefined' && require.main === module) {
+  if (ENVIRONMENT_IS_NODE && require.main === module) {
       var fs = require('fs');
       var heap_size = 128 * 1024;
       var contents = '';