如果先发出然后监听，节点JS事件发射器将无法工作

Question

var events=require('events').EventEmitter;
var eventEmitter = new events();


eventEmitter.on('hello', function()
{ 
  console.log('Hey !!');
});

eventEmitter.emit('hello');

now if i first emit and then listen it will not print console.Help me to find the reason.

Answer 1

EventEmitter delivers events synchronously, which means that when you emit a message, that message is delivered to any listeners right away.

If you first emit and then listen, you're listening too late because the message has already been delivered.