!!$('nothing').eq(0) is true, and !!$('nothing')[0] is false

[vvenv]

以下代码，!!element，总是返回 true，建议的解决是 var element = $(selector)[0] 或采用length判断

 Widget.query = function(selector) {
    var element = $(selector).eq(0)
    var cid

    element && (cid = element.attr(DATA_WIDGET_CID))
    return cachedInstances[cid]
  }