ez wrapping

wrapper.js

'use strict'

const Emitter = require('events')
const oldEmitter = Emitter.prototype.emit
Emitter.prototype.emit = function wrappedEmit(ev) {
  const start = Date.now()
  const res = oldEmitter.apply(this, arguments)
  console.log(`emitting ${ev} on ${this.constructor} took ${Date.now() - start} ms`)
  return res
}

const x = new Emitter()
x.on('testing', function timeWaster() {
  const start = Date.now()
  while (Date.now() - start < 1000) {}
})

x.emit('testing')