nodeEventTarget.once(type, listener[, options])


    EventTarget 类的 Node.js 特定扩展,它为给定的事件 type 添加了 once 监听器。 这相当于调用 on 并将 once 选项设置为 true

    Node.js-specific extension to the EventTarget class that adds a once listener for the given event type. This is equivalent to calling on with the once option set to true.