Restructed async load function

src/library_browser.js

@@ -766,55 +766,83 @@ var LibraryBrowser = {
     safeSetTimeout(() => _emscripten_run_script(script), millis);
   },
 
-  // TODO: currently not callable from a pthread, but immediately calls onerror() if not on main thread.
-  emscripten_async_load_script__deps: ['$UTF8ToString'],
-  emscripten_async_load_script: (url, onload, onerror) => {
-    url = UTF8ToString(url);
+  function promiseToCallbacks(promise, onload, onerror) {
+
     onload = {{{ makeDynCall('v', 'onload') }}};
     onerror = {{{ makeDynCall('v', 'onerror') }}};
+    promise.then(onload).catch(onerror);
+
+  }
 
-#if PTHREADS
-    if (ENVIRONMENT_IS_PTHREAD) {
-      err(`emscripten_async_load_script("${url}") failed, emscripten_async_load_script is currently not available in pthreads!`);
-      return onerror ? onerror() : undefined;
-    }
-#endif
-#if ASSERTIONS
-    assert(runDependencies === 0, 'async_load_script must be run when no other dependencies are active');
-#endif
-    {{{ runtimeKeepalivePush() }}}
+  function callbacksToPromise(func, onload, onerror) {
+  return new Promise((resolve, reject) => {
+    func((result) => {
+      var onload = {{{ makeDynCall('v', 'onload') }}};
+      onload();
+      resolve(result);
+    }, (error) => {
+      var onerror = {{{ makeDynCall('v', 'onerror') }}};
+      onerror();
+      reject(error);
+    });
+  });
+}
+
+
+  emscripten_async_load_script_promise__deps: ['$UTF8ToString'],
+  emscripten_async_load_script_promise: (url) => {
+    url = UTF8ToString(url);
 
-    var loadDone = () => {
-      {{{ runtimeKeepalivePop() }}}
-      if (onload) {
-        if (runDependencies > 0) {
-          dependenciesFulfilled = onload;
-        } else {
-          onload();
-        }
+    // Creating a promise for script loading functionality
+    return new Promise((resolve, reject) => {
+      #if PTHREADS
+      if (ENVIRONMENT_IS_PTHREAD) {
+        err(`emscripten_async_load_script("${url}") failed, emscripten_async_load_script is currently not available in pthreads!`);
+        return reject('emscripten_async_load_script is not available for pthreads');
       }
-    }
+      #endif
+
+      #if ASSERTIONS
+      assert(runDependencies === 0, 'async_load_script must be run when no other dependencies are active');
+      #endif
+
+      {{{ runtimeKeepalivePush() }}}
 
-    var loadError = () => {
-      {{{ runtimeKeepalivePop() }}}
-      onerror?.();
-    };
+      var loadDone = () => {
+        {{{ runtimeKeepalivePop() }}}
+        resolve();
+      }
+
+      var loadError = () => {
+        {{{ runtimeKeepalivePop() }}}
+        reject();
+      };
+
+      #if ENVIRONMENT_MAY_BE_NODE && DYNAMIC_EXECUTION
+      if (ENVIRONMENT_IS_NODE) {
+        readAsync(url, (data) => {
+          eval(data);
+          loadDone();
+        }, loadError, false);
+        return;
+      }
+      #endif
+
+      var script = document.createElement('script');
+      script.onload = loadDone;
+      script.onerror = loadError;
+      script.src = url;
+      document.body.appendChild(script);
+
+    });
+  },
 
-#if ENVIRONMENT_MAY_BE_NODE && DYNAMIC_EXECUTION
-    if (ENVIRONMENT_IS_NODE) {
-      readAsync(url, (data) => {
-        eval(data);
-        loadDone();
-      }, loadError, false);
-      return;
-    }
-#endif
 
-    var script = document.createElement('script');
-    script.onload = loadDone;
-    script.onerror = loadError;
-    script.src = url;
-    document.body.appendChild(script);
+  // Refactored the function to implement the promise based functionality and backward compatibility with callbacks
+  emscripten_async_load_script__deps: ['$emscripten_async_load_script_promise', '$UTF8ToString', '$promiseToCallbacks'],
+  emscripten_async_load_script: function(url, onload, onerror)  {
+      var promise = emscripten_async_load_script_promise(url);
+      promiseToCallbacks(promise, onload, onerror);
   },
 
   // Runs natively in pthread, no __proxy needed.