waitgroup.js

var wait = require('waitgroup')
var fs = require('fs')

var wg = new wait

var list = ['file1.txt','file2.txt','file3.txt','file4.txt']

list.forEach(function(val) {
  wg.add()
  fs.readFile(val,{"encoding":"UTF-8"},function(e,data) {
    if(e) console.log(e)
    else console.log(data)
    wg.done()
  })
})

wg.wait(function() {
  console.log("All Open!")
})