emsdk/upstream/emscripten/test/browser/test_async_mainloop.c

// Copyright 2015 The Emscripten Authors.  All rights reserved.
// Emscripten is available under two separate licenses, the MIT license and the
// University of Illinois/NCSA Open Source License.  Both these licenses can be
// found in the LICENSE file.

#include <stdio.h>
#include <emscripten.h>
#include <assert.h>

void finish(int result) {
  assert(result == 121);
  emscripten_force_exit(0);
}

int counter = 0;
int nesting = 0;

void iter() {
  printf("frame: %d\n", ++counter);

  // ensure we don't 'recurse' with the main loop sending us back in before the
  // synchronous operation callback finishes the rest of this trace
  assert(nesting == 0);
  nesting++;
  emscripten_sleep(500);
  assert(nesting == 1);
  nesting = 0;

  if (counter == 10) {
    finish(121); // if we got here without hitting any assertions, all is well
    emscripten_cancel_main_loop();
  }
}

int main() {
  emscripten_set_main_loop(iter, 0, 0);
}