waitFor port for `phantomjs-node`

phantomjs-waitFor.js

var async = require('async');

module.exports = waitFor;

/**
 * waitFor port used with 
 * @see    {@link https://github.com/ariya/phantomjs/blob/master/examples/waitfor.js}
 * @see    {@link https://github.com/sgentle/phantomjs-node}
 * @callback testFx - Test function, will repeat until true or timeout limit is reached
 * @callback onReady - Fires if/when `testFx` passes.
 * @param {(number|boolean|string)} [timeOut=false] - If defined and falsey or string value of`forever` 
 *                                                    then `waitFor` will run until `testFx` passes without 
 *                                                    timing out, otherwise pass a number in miliseconds.
 */
function waitFor(testFx, onReady, timeOut) {

  var maxtimeOutMillis = typeof timeOut !== 'undefined' ? timeOut : 5000 // Default Max Timout is 5s if not defined
    , start = new Date().getTime()
    , isAsync = testFx.length > 0
    , passing = undefined
  ;

  async.until(
    function Test() { 
      return typeof passing !== 'undefined'; 
    },
    function Action(cb) {
      setTimeout(function(){

        if (!maxtimeOutMillis || maxtimeOutMillis == 'forever' || new Date().getTime() - start < maxtimeOutMillis) {

          // If a callback is passed to `testFx` we'll handle that.
          function useCallback(){
            passing = arguments[0]
            return cb();
          };                    

          passing = (function(){
            return (typeof(testFx) === "string" ? eval(testFx) : testFx).apply(this, arguments);
          })(isAsync ? useCallback : undefined);

          if(!isAsync) cb();

        } else {
          return cb(new Error('`waitFor` timeout'));
        }

      }, 250);
    },
    function Done(err) {
      return (function(){
        return (typeof(onReady) === "string" ? eval(onReady) : onReady).apply(this, arguments);                  
      })(err, passing);
    }
  );

}

usage.js

var PhantomJS = require('phantom');
var waitFor = require('./phantomjs-waitFor');
var util = require('util');

PhantomJS.create(function phantom(ph){
  ph.createPage(function(page){
    page.open('https://www.google.com', function(status){
      if(status !== 'fail'){

        // required for an example below
        page.set('onUrlChanged', function(url){
          page.url = url;
        });
        
        /**
         * As a simple example lets say we want to render an image of the google home page
         * only after the logo has loaded ... (not the best example, but you should get the idea)
         * @callback cb - waitFor's testFx callback can pass the results to a callback 
         *                or return the value directly, heres the callback example
         */
        waitFor(function Test(cb){

          page.evaluate(function(){
            return document.getElementById("hplogo").outerHTML;
          }, function(logo){
            cb(logo)
          });

        }, function(err, pass){
          if(pass){
            page.render('./google.jpg', function(){
              console.log("render complete");
              ph.exit();
            });
          } else {
            console.error(err);
            ph.exit()
          }
        }, 3000)

        /**
         * And heres an example with a basic return
         * ***
         * *** Note that lack of a `cb` argument, if you include a `cb` arg 
         * *** and don't provide it then the `testFx` never passes
         * ***
         * Here we'll render a screenshot for every results page
         */
        waitFor(function Test(){
          return /google\.com\/webhp.+q=/g.test(page.url);
        }, function(err, pass){
          if(pass){
            var match = page.url.match(/^http[s]?:\/\/www\.google\.com\/webhp\?.*start=(\d+)/i);
            var badImageFileName = util.format("./results_page_%d.jpg", match ? (parseInt(match[1]) + 10)/10 : 1);
            page.render(badImageFileName, function(){
              console.log("render complete");
              ph.exit();
            });
          } else {
            console.error(err);
            ph.exit()
          }
        }, 3000)

      }

    })
  })
})

this example didn't work for me using:
"phantom": "^4.0.3",
on a node controller normal get endpoint