emscripten_async_load_script

src/library_browser.js

@@ -688,6 +688,25 @@ mergeInto(LibraryManager.library, {
     }, millis);
   },
 
+  emscripten_async_load_script: function(url, onload, onerror) {
+    Module['noExitRuntime'] = true;
+
+    onload = Runtime.getFuncWrapper(onload, 'v');
+
+    assert(runDependencies === 0, 'async_load_script must be run when no other dependencies are active');
+    var script = document.createElement('script');
+    script.onload = function() {
+      if (runDependencies > 0) {
+        dependenciesFulfilled = onload;
+      } else {
+        onload();
+      }
+    };
+    script.onerror = onerror;
+    script.src = Pointer_stringify(url);
+    document.body.appendChild(script);
+  },
+
   emscripten_set_main_loop: function(func, fps, simulateInfiniteLoop) {
     Module['noExitRuntime'] = true;
 

system/include/emscripten/emscripten.h

@@ -45,8 +45,26 @@ extern "C" {
 extern void emscripten_run_script(const char *script);
 extern int emscripten_run_script_int(const char *script);
 extern char *emscripten_run_script_string(const char *script); // uses a single buffer - shared between calls!
+
+/*
+ * Asynchronously run a script, after a specified amount of
+ * time.
+ */
 extern void emscripten_async_run_script(const char *script, int millis);
 
+/*
+ * Asynchronously loads a script from a URL.
+ *
+ * This integrates with the run dependencies system, so your
+ * script can call addRunDependency multiple times, prepare
+ * various asynchronous tasks, and call removeRunDependency
+ * on them; when all are complete (or there were no run
+ * dependencies to begin with), onload is called. An example use
+ * for this is to load an asset module, that is, the output of the
+ * file packager.
+ */
+extern void emscripten_async_load_script(const char *script, void (*onload)(), void (*onerror)());
+
 /*
  * Set a C function as the main event loop. The JS environment
  * will call that function at a specified number of frames per

tests/emscripten_api_browser2.cpp

@@ -0,0 +1,53 @@
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+
+#include<emscripten.h>
+
+int value = 0;
+
+extern "C" {
+  void set(int x) {
+    printf("set! %d\n", x);
+    value = x;
+  }
+}
+
+void load2() {
+  printf("load2\n");
+
+  char buffer[10];
+  memset(buffer, 0, 10);
+  FILE *f = fopen("file1.txt", "r");
+  fread(buffer, 1, 5, f);
+  fclose(f);
+  assert(strcmp(buffer, "first") == 0);
+
+  memset(buffer, 0, 10);
+  f = fopen("file2.txt", "r");
+  fread(buffer, 1, 6, f);
+  fclose(f);
+  assert(strcmp(buffer, "second") == 0);
+
+  int result = 1;
+  REPORT_RESULT();
+}
+void error2() {
+  printf("fail2\n");
+}
+
+void load1() {
+  printf("load1\n");
+  assert(value == 456);
+  emscripten_async_load_script("script2.js", load2, error2);
+}
+void error1() {
+  printf("fail1\n");
+}
+
+int main() {
+  emscripten_async_load_script("script1.js", load1, error1);
+
+  return 1;
+}
+

tests/test_browser.py

@@ -1230,6 +1230,17 @@ keydown(100);keyup(100); // trigger the end
   def test_emscripten_api(self):
     self.btest('emscripten_api_browser.cpp', '1', args=['-s', '''EXPORTED_FUNCTIONS=['_main', '_third']'''])
 
+  def test_emscripten_api2(self):
+    open('script1.js', 'w').write('''
+      Module._set(456);
+    ''')
+
+    open('file1.txt', 'w').write('first');
+    open('file2.txt', 'w').write('second');
+    Popen([PYTHON, FILE_PACKAGER, 'test.data', '--preload', 'file1.txt', 'file2.txt'], stdout=open('script2.js', 'w')).communicate()
+
+    self.btest('emscripten_api_browser2.cpp', '1', args=['-s', '''EXPORTED_FUNCTIONS=['_main', '_set']'''])
+
   def test_emscripten_api_infloop(self):
     self.btest('emscripten_api_browser_infloop.cpp', '7')