Grunt task to wait for a port to become open

Gruntfile.js

'use strict';

var portscanner = require('portscanner');
var port = 3001;

module.exports = function (grunt) {

  grunt.registerTask('waitForPort', 'Waits until a port is open', function() {
    grunt.log.write('Waiting to the development server to come online...');
    var done = this.async();
    var timer = setInterval(function () {
      portscanner.checkPortStatus(port, 'localhost', function (error, status) {
        if (status === 'open') {
          clearInterval(timer);
          grunt.log.writeln('ready.');
          done();
        }
        else {
          grunt.log.write('.');
        }
      });
    }, 50);
  });

});