当被调用时,则只要 Timeout 处于活动状态,就会要求 Node.js 事件循环不要退出。 多次调用 timeout.ref() 没有影响。

默认情况下,所有的 Timeout 对象都是 ref 的,通常不需要调用 timeout.ref(),除非之前调用了 timeout.unref()

When called, requests that the Node.js event loop not exit so long as the Timeout is active. Calling timeout.ref() multiple times will have no effect.

By default, all Timeout objects are "ref'ed", making it normally unnecessary to call timeout.ref() unless timeout.unref() had been called previously.