jquery - 多次丢弃事件后的警报触发

Question

我得承认，我几乎是一个菜鸟，但我一直在努力解决这个问题。我必须if在两次下降发生后触发，现在它在加载时触发。我在那里想念什么？

$(function() {
    $( "#draggable" ).draggable({
        revert: "invalid",
        snap: "#droppable",
    });
    $( "#droppable" ).droppable({
        accept: "#draggable",
        drop: function() {
            $("#whistle").get(0).play();
            $(this).data(droppable)
        }
    });
    $( "#draggable2" ).draggable({
        revert: "invalid",
        snap: "#droppable",
    });
    $( "#droppable2" ).droppable({
        accept: "#draggable2",
        drop: function() {
            $("#whistle").get(0).play();
            $(this).data(droppable2)
        }
    });
    if ($.queue(2)) {
        $("#whistle2").get(0).play();
        alert ("done!")
    }
});

Answer 1

您可以使用两个$.Deferreds 及其promise-objects 来触发您的处理程序：

$(function() {

    var dfd1 = $.Deferred();
    var dfd2 = $.Deferred();

    $( "#draggable" ).draggable({
        revert: "invalid",
        snap: "#droppable",
    });
    $( "#droppable" ).droppable({
        accept: "#draggable",
        drop: function() {
            $("#whistle").get(0).play();
            $(this).data(droppable);
            dfd1.resolve();
        }
    });
    $( "#draggable2" ).draggable({
        revert: "invalid",
        snap: "#droppable",
    });
    $( "#droppable2" ).droppable({
        accept: "#draggable2",
        drop: function() {
            $("#whistle").get(0).play();
            $(this).data(droppable2);
            dfd2.resolve();
        }
    });
    //this will trigger when both dfds have been resolved
    $.when(dfd1.promise(), dfd2.promise()).then(function(){
        $("#whistle2").get(0).play();
        alert ("done!")
    });
});

查看这个小提琴的演示（单击两个按钮，看看魔术发生了！）并阅读$.Deferred和$.when