利用者の要求に応じて新しいウィンドウを開くために、プログレッシブエンハンスメントを使用する

事例 1

マークアップ:

スクリプトはドキュメントの head 要素内に組み込まれており、リンクにはスクリプトのフックとなる id 属性がある。

<script type="text/javascript" src="popup.js"></script>
…
<a href="help.html" id="newwin">Show Help</a>

スクリプト:

 
// Use traditional event model whilst support for event registration
// amongst browsers is poor.
window.onload = addHandlers;

function addHandlers()
{
  var objAnchor = document.getElementById('newwin');

  if (objAnchor)
  {
    objAnchor.firstChild.data = objAnchor.firstChild.data + ' (opens in a new window)';
    objAnchor.onclick = function(event){return launchWindow(this, event);}
    // UAAG requires that user agents handle events in a device-independent manner
    // but only some browsers do this, so add keyboard event to be sure
    objAnchor.onkeypress = function(event){return launchWindow(this, event);}
  }
}

function launchWindow(objAnchor, objEvent)
{
  var iKeyCode, bSuccess=false;

  // If the event is from a keyboard, we only want to open the
  // new window if the user requested the link (return or space)
  if (objEvent && objEvent.type == 'keypress')
  {
    if (objEvent.keyCode)
      iKeyCode = objEvent.keyCode;
    else if (objEvent.which)
      iKeyCode = objEvent.which;

    // If not carriage return or space, return true so that the user agent
    // continues to process the action
    if (iKeyCode != 13 && iKeyCode != 32)
      return true;
  }

  bSuccess = window.open(objAnchor.href);

  // If the window did not open, allow the browser to continue the default
  // action of opening in the same window
  if (!bSuccess)
    return true;

  // The window was opened, so stop the browser processing further
  return false;
}