[chromedriver] Implement command: executeAsyncScript and setScriptTimeout

chrome/test/chromedriver/js/execute_async_script.js

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/**
+* Return the information of asynchronous script execution.
+*
+* @return {Object.<string, ?>} Information of asynchronous script execution.
+*/
+function getAsyncScriptInfo() {
+  var key = 'chromedriverAsyncScriptInfo';
+  if (!(key in document))
+    document[key] = {'id': 0, 'finished': false};
+  return document[key];
+}
+
+/**
+* Execute the given script and save its asynchronous result.
+*
+* If script1 finishes after script2 is executed, then script1's result will be
+* discarded while script2's will be saved.
+*
+* @param {!string} script The asynchronous script to be executed.
+* @param {Array.<*>} args Arguments to be passed to the script.
+* @param {!number} timeout The timeout for the asynchronous script.
+*/
+function executeAsyncScript(script, args, timeout) {
+  var info = getAsyncScriptInfo();
+  info.id++;
+  info.finished = false;
+  delete info.result;
+  var id = info.id;
+
+  function callback(result) {
+    if (id == info.id) {
+      info.result = result;
+      info.finished = true;
+    }
+  }
+  args.push(callback);
+
+  try {
+    new Function(script).apply(null, args);
+  } catch (error) {
+    error.code = 17;  // Error code for JavaScriptError.
+    throw error;
+  }
+
+  function clearResultIfTimeout() {
+    if (id == info.id) {
+      delete info.result;  // Delete reference to result if it is already set.
+      info.id++;  // Prevent the script from setting the result if not yet.
+    }
+  }
+  // Allow C++ to pull result in 5 seconds before deletion.
+  setTimeout(clearResultIfTimeout, timeout + 5000);

[chrisgao (Use stgao instead), 2013/03/08 23:28:25]

I think 5 seconds should be long enough for C++ to get the result.

Another reliable way to clear the result is in C++:
1. Clear the ref during pulling result if it is set.
2. Execute "var info = document.chromedriverAsyncScriptInfo; info.id++; delete
info.result;" if we timeout.

Which one do you prefer?

+}