好吧，可行的方法是将焦点"处理程序绑定到所有内容，并且您知道当您不在<div>中时另一个焦点"事件.

Well, what might work would be to bind a "focus" handler to everything, and you know when you're not in the <div> when you get a "focus" event elsewhere.

$('body').live('focus', (function() {
  var inDiv = false;
  return function(e) {
    if ($(this).closest('#theDiv').length)
      inDiv = true;
    else {
      if (inDiv)
        alert("just lost focus!");
      inDiv = false;
    }
  };
 });