在开始之前取消拖动

我正在使用jQuery UI可排序,如果条件为真,我只是试图阻止拖动.我遇到过这个解决方案:https://stackoverflow.com/a/18470982/3758078但是在拖动停止时取消阻止,而不是在它开始之前.其他解决方案建议return false;在sort:事件中使用,但这只会返回错误.

    $(elements).sortable({
        start: function() {
           if( true ) {
               //cancel dragging before it begins
           }
        }
    });

Dekel.. 5

这是一个使用start回调的工作示例.
您可以使用该allowdrag复选框启用/禁用拖动功能:

$(document).ready(function () {
    $("#draggable").draggable({
      revert: "invalid",
      start: function(e) {
        if (!$('#allowdrag').is(':checked')) {
          e.preventDefault();
        }
      }
    });
    $("#Dropable").droppable({
        activeClass: "ui-state-highlight",
        drop: function (event, ui) {
            alert("dropped!");
        },
        tolerance: 'fit'
    });
});

#draggable {
    width: 150px;
    height: 150px;
    padding: 0.5em;
}
#Dropable {
    height:300px;
    width:400px;
    border: 2px solid red;
}

 Allow drag


    
Drag me around

Droppable area

$(document).ready(function () {
    $("#draggable").draggable({
      revert: "invalid",
      start: function(e) {
        if (!$('#allowdrag').is(':checked')) {
          e.preventDefault();
        }
      }
    });
    $("#Dropable").droppable({
        activeClass: "ui-state-highlight",
        drop: function (event, ui) {
            alert("dropped!");
        },
        tolerance: 'fit'
    });
});

#draggable {
    width: 150px;
    height: 150px;
    padding: 0.5em;
}
#Dropable {
    height:300px;
    width:400px;
    border: 2px solid red;
}

 Allow drag


    
Drag me around

Droppable area