Question

I am just getting started with this, but I am wondering how could I take the very simple example below and modify so that if the draggable div is already placed on the droppable div it won’t fire the alert.

      <script type="text/javascript">
          $(function () {
              $("#draggable-1").draggable();
              $("#draggable-2").draggable();


              $("#droppable").droppable({
                  drop: function (event, ui) {
                      var currentId = $(ui.draggable).attr('id');

                      if (currentId == "draggable-1") {
                          $(this)

                          // would like to prevent this if draggable is already dropped!
                          alert("Adding Item #1.")


                      } else {
                          $(this)
                          alert("Adding Item #2.")
                      }
                  }
              });
          });
      </script>
    <table width="100%"><tr><th>Draggable</th><th>Order Section</th><tr><td>
    <div id="draggable-1">
        <p>Item #1</p>
    </div>

    <div id="draggable-2">
        <p>Item #2.</p>
    </div>

    <div id="droppable">
        <p>Add Your Item</p>  
    </div>

Answer 1

One solution that worked for me:

var wasInDrop = false;
var finishInDrop = false;
$("#draggable_1").draggable({
    start:  function(event, ui){
            if (! finishInDrop){
                wasInDrop = false;
            }
            finishInDrop = false; //will be set to true if landing in drop.
        },
    stop:     function(event, ui){
            if (finishInDrop && !wasInDrop){
                          alert("Adding Item #1.");
            }
            if (finishInDrop){ wasInDrop=true;}

        }
    });

$("#droppable").droppable({
    drop: function (event, ui) {
        $(this)
        var currentId = $(ui.draggable).attr('id');
        if (currentId == "draggable_1") {
            finishInDrop = true; //for this time.
        }
    });

And so forth. The idea is that the draggable fires the alert, if:

1. It finishes inside droppable.
2. It didn’t start inside droppable.