Instructions for using the events.EventEmitter.listenerCount method in node.js_node.js

Method description:

Returns the number of listeners registered for the specified event.

Syntax:

Copy code The code is as follows:

EventEmitter.listenerCount(emitter, event)

Receive parameters:

emitter Event Emitter
event event

Example:

Copy code The code is as follows:

if(events.EventEmitter.listenerCount(this, 'feedback') == 0) {
//....
}

Source code:

Copy code The code is as follows:

EventEmitter.listenerCount = function(emitter, type) {
var ret;
if (!emitter._events || !emitter._events[type])
ret = 0;
else if (util.isFunction(emitter._events[type]))
ret = 1;
else
ret = emitter._events[type].length;
Return ret;
};