tests/browser/cwrap_early.js

Module['preRun'].push(function() {
  console.log('preRun');
  // it is ok to call cwrap before the runtime is loaded. we don't need the code
  // and everything to be ready, since cwrap just prepares to call code, it 
  // doesn't actually call it
  var wrappedAdd = Module['cwrap']('add', 'number', ['number', 'number']);
  // but to call the compiled code, we must wait for the runtime
  Module['onRuntimeInitialized'] = function() {
    console.log('onRuntimeInitialized');
    if (wrappedAdd(5, 6) != 11) throw '5 + 6 should be 11';
    // report success
    var xhr = new XMLHttpRequest();
    xhr.open('GET', 'http://localhost:8888/report_result?0', true);
    xhr.send();
    setTimeout(function() { window.close() }, 1000);
  };
});