gecko/testing/mochitest/tests/SimpleTest/EventUtils.js

/**
 * EventUtils provides some utility methods for creating and sending DOM events.
 * Current methods:
 *  sendMouseEvent
 *  sendChar
 *  sendString
 *  sendKey
 */

/**
 * Send a mouse event to the node with id aTarget. The "event" passed in to
 * aEvent is just a JavaScript object with the properties set that the real
 * mouse event object should have. This includes the type of the mouse event.
 * E.g. to send an click event to the node with id 'node' you might do this:
 *
 * sendMouseEvent({type:'click'}, 'node');
 */
function sendMouseEvent(aEvent, aTarget) {
  if (['click', 'mousedown', 'mouseup', 'mouseover', 'mouseout'].indexOf(aEvent.type) == -1) {
    throw new Error("sendMouseEvent doesn't know about event type '"+aEvent.type+"'");
  }

  // For events to trigger the UA's default actions they need to be "trusted"
  netscape.security.PrivilegeManager.enablePrivilege('UniversalBrowserWrite');

  var event = document.createEvent('MouseEvent');

  var typeArg          = aEvent.type;
  var canBubbleArg     = true;
  var cancelableArg    = true;
  var viewArg          = window;
  var detailArg        = aEvent.detail        || (aEvent.type == 'click'     ||
                                                  aEvent.type == 'mousedown' ||
                                                  aEvent.type == 'mouseup' ? 1 : 0);
  var screenXArg       = aEvent.screenX       || 0;
  var screenYArg       = aEvent.screenY       || 0;
  var clientXArg       = aEvent.clientX       || 0;
  var clientYArg       = aEvent.clientY       || 0;
  var ctrlKeyArg       = aEvent.ctrlKey       || false;
  var altKeyArg        = aEvent.altKey        || false;
  var shiftKeyArg      = aEvent.shiftKey      || false;
  var metaKeyArg       = aEvent.metaKey       || false;
  var buttonArg        = aEvent.button        || 0;
  var relatedTargetArg = aEvent.relatedTarget || null;

  event.initMouseEvent(typeArg, canBubbleArg, cancelableArg, viewArg, detailArg,
                       screenXArg, screenYArg, clientXArg, clientYArg,
                       ctrlKeyArg, altKeyArg, shiftKeyArg, metaKeyArg,
                       buttonArg, relatedTargetArg);

  document.getElementById(aTarget).dispatchEvent(event);
}

/**
 * Send the char aChar to the node with id aTarget.  If aTarget is not
 * provided, use "target".  This method handles casing of chars (sends the
 * right charcode, and sends a shift key for uppercase chars).  No other
 * modifiers are handled at this point.
 *
 * For now this method only works for English letters (lower and upper case)
 * and the digits 0-9.
 *
 * Returns true if the keypress event was accepted (no calls to preventDefault
 * or anything like that), false otherwise.
 */
function sendChar(aChar, aTarget) {
  // DOM event charcodes match ASCII (JS charcodes) for a-zA-Z0-9.
  var hasShift = (aChar == aChar.toUpperCase());
  var charCode = aChar.charCodeAt(0);
  var keyCode = charCode;
  if (!hasShift) {
    // For lowercase letters, the keyCode is actually 32 less than the charCode
    keyCode -= 0x20;
  }

  return __doEventDispatch(aTarget, charCode, keyCode, hasShift);
}

/**
 * Send the string aStr to the node with id aTarget.  If aTarget is not
 * provided, use "target".
 *
 * For now this method only works for English letters (lower and upper case)
 * and the digits 0-9.
 */
function sendString(aStr, aTarget) {
  for (var i = 0; i < aStr.length; ++i) {
    sendChar(aStr.charAt(i), aTarget);
  }
}

/**
 * Send the non-character key aKey to the node with id aTarget. If aTarget is
 * not provided, use "target".  The name of the key should be a lowercase
 * version of the part that comes after "DOM_VK_" in the KeyEvent constant
 * name for this key.  No modifiers are handled at this point.
 *
 * Returns true if the keypress event was accepted (no calls to preventDefault
 * or anything like that), false otherwise.
 */
function sendKey(aKey, aTarget) {
  keyName = "DOM_VK_" + aKey.toUpperCase();

  if (!KeyEvent[keyName]) {
    throw "Unknown key: " + keyName;
  }

  return __doEventDispatch(aTarget, 0, KeyEvent[keyName], false);
}

/**
 * Actually perform event dispatch given a charCode, keyCode, and boolean for
 * whether "shift" was pressed.  Send the event to the node with id aTarget.  If
 * aTarget is not provided, use "target".
 *
 * Returns true if the keypress event was accepted (no calls to preventDefault
 * or anything like that), false otherwise.
 */
function __doEventDispatch(aTarget, aCharCode, aKeyCode, aHasShift) {
  if (aTarget === undefined) {
    aTarget = "target";
  }

  // Make our events trusted
  netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");

  var event = document.createEvent("KeyEvents");
  event.initKeyEvent("keydown", true, true, document.defaultView,
                     false, false, aHasShift, false,
                     aKeyCode, 0);
  var accepted = $(aTarget).dispatchEvent(event);

  // Cancelling keydown cancels keypress too
  if (accepted) {
    event = document.createEvent("KeyEvents");
    if (aCharCode) {
      event.initKeyEvent("keypress", true, true, document.defaultView,
                         false, false, aHasShift, false,
                         0, aCharCode);
    } else {
      event.initKeyEvent("keypress", true, true, document.defaultView,
                         false, false, aHasShift, false,
                         aKeyCode, 0);
    }
    accepted = $(aTarget).dispatchEvent(event);
  }

  // Always send keyup
  var event = document.createEvent("KeyEvents");
  event.initKeyEvent("keyup", true, true, document.defaultView,
                     false, false, aHasShift, false,
                     aKeyCode, 0);
  $(aTarget).dispatchEvent(event);
  return accepted;
}