conditional statements - javascript WAIT for something to be true

i create in a javascript function a prototype window. in the window i load a site where the user has to select something. i want the javascript function to wait until the user selected something and then return the value of the what the user selected.

function showTargetDirectoryChooser(){
  var win = new Window( 'dirchooser_' + new Date().getTime() , {className: 'alphacube', width: 320, height: 470, url: '/directories/choose', maximizable: false});
  win.showCenter();
  win.setDestroyOnClose();

  // WAIT_UNTIL( win.content.contentWindow.Directory != null )

  return win.content.contentWindow.Directory
}

i found here something i could maybe use - but i dont understand how to...

Answer

This is an asynchronous process; it’s probably better to handle this with a callback.

For example, couldn’t you use a closeCallback?

function showTargetDirectoryChooser(done){
  var win = new Window( 'dirchooser_' + new Date().getTime() , {className: 'alphacube', width: 320, height: 470, url: '/directories/choose', maximizable: false});
  win.showCenter();
  win.setDestroyOnClose();

  // This will ensure 
  win.setCloseCallback(function () {
      done(win.content.contentWindow.Directory);
      return true; // or return false if you don't want the window to be closed
  });

  return true;
}

With this, you would change

var chosenDir = showTargetDirectoryChooser();
// do something with chosen directory

into

var chosenDir;
showTargetDirectoryChooser(function (directory) {
    chosenDir = directory;
    // do something with the chosen directory
});