WEB-INF和/ src / main / resources文件夹有什么区别？(What is the difference between WEB-INF and /src/main/resources folders?)

 每次输入span ，都会绑定该跨度的mouseleave处理程序。 因此，如果您多次输入跨度，当您离开它时，您将多次运行mouseleave处理程序。 其中每个都将调用setTimeout() ，但f将仅设置为最后一个。 因此，当您稍后执行clearTimeout(f) ，它只会清除其中一个，其他的继续运行。 
 
 将一个事件处理程序绑定到另一个事件处理程序中几乎是不对的。 事件处理程序通常应在顶层定义。 如果您希望一个处理程序依赖于某个其他处理程序是否先运行，请使用变量来跟踪它。 

Every time you enter a span, you bind a mouseleave handler for that span. So if you enter a span multiple times, when you leave it you'll run the mouseleave handler multiple times. Each of these will call setTimeout(), but f will only be set to the last one. So when you later do clearTimeout(f), it only clears one of them, the others continue to run.
 
It's almost never right to bind one event handler inside another event handler. Event handlers should usually be defined at the top level. If you want one handler to be dependent on whether some other handler has run first, use a variable to keep track of it.