immediate.ref()

• 返回：<Immediate> 参考 immediate

  ¥Returns: <Immediate> a reference to immediate

调用时，请求只要 Immediate 处于活动状态，Node.js 事件循环就不会退出。多次调用 immediate.ref() 将不起作用。

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

默认情况下，所有 Immediate 对象都是 "引用的"，因此通常无需调用 immediate.ref()，除非之前已调用 immediate.unref()。

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