immediate.ref()

• 返回：<Immediate> 一个对 immediate 的引用

当被调用时，只要 Immediate 活跃，请求 Node.js 事件循环不要退出。多次调用 immediate.ref() 不会有任何效果。

🌐 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 对象都是被“引用”的，通常不需要调用 immediate.ref()，除非之前调用过 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.