How to scroll down with Phantomjs to load dynamic content

Question

I am trying to scrape links from a page that generates content dynamically as the user scroll down to the bottom (infinite scrolling). I have tried doing different things with Phantomjs but not able to gather links beyond first page. Let say the element at the bottom which loads content has class .has-more-items. It is available until final content is loaded while scrolling and then becomes unavailable in DOM (display:none). Here are the things I have tried-

• Setting viewportSize to a large height right after var page = require('webpage').create();

page.viewportSize = { width: 1600, height: 10000, };

• Using page.scrollPosition = { top: 10000, left: 0 } inside page.open but have no effect like-

page.open('http://example.com/?q=houston', function(status) {
   if (status == "success") {
      page.scrollPosition = { top: 10000, left: 0 };  
   }
});

• Also tried putting it inside page.evaluate function but that gives

Reference error: Can't find variable page

• Tried using jQuery and JS code inside page.evaluate and page.open but to no avail-

$("html, body").animate({ scrollTop: $(document).height() }, 10, function() { //console.log('check for execution'); });

as it is and also inside document.ready. Similarly for JS code-

window.scrollBy(0,10000)

as it is and also inside window.onload

I am really struck on it for 2 days now and not able to find a way. Any help or hint would be appreciated.

Update

I have found a helpful piece of code at https://groups.google.com/forum/?fromgroups=#!topic/phantomjs/8LrWRW8ZrA0

var hitRockBottom = false; while (!hitRockBottom) {
    // Scroll the page (not sure if this is the best way to do so...)
    page.scrollPosition = { top: page.scrollPosition + 1000, left: 0 };

    // Check if we've hit the bottom
    hitRockBottom = page.evaluate(function() {
        return document.querySelector(".has-more-items") === null;
    }); }

Where .has-more-items is the element class I want to access which is available at the bottom of the page initially and as we scroll down, it moves further down until all data is loaded and then becomes unavailable.

However, when I tested it is clear that it is running into infinite loops without scrolling down (I render pictures to check). I have tried to replace page.scrollPosition = { top: page.scrollPosition + 1000, left: 0 }; with codes from below as well (one at a time)

window.document.body.scrollTop = '1000';
location.href = ".has-more-items";
page.scrollPosition = { top: page.scrollPosition + 1000, left: 0 };
document.location.href=".has-more-items";

But nothing seems to work.

Answer 1

Found a way to do it and tried to adapt to your situation. I didn't test the best way of finding the bottom of the page because I had a different context, but check the solution below. The thing here is that you have to wait a little for the page to load and javascript works asynchronously so you have to use setInterval or setTimeout (see) to achieve this.

page.open('http://example.com/?q=houston', function () {

  // Check for the bottom div and scroll down from time to time
  window.setInterval(function() {
      // Check if there is a div with class=".has-more-items" 
      // (not sure if there's a better way of doing this)
      var count = page.content.match(/class=".has-more-items"/g);

      if(count === null) { // Didn't find
        page.evaluate(function() {
          // Scroll to the bottom of page
          window.document.body.scrollTop = document.body.scrollHeight;
        });
      }
      else { // Found
        // Do what you want
        ...
        phantom.exit();
      }
  }, 500); // Number of milliseconds to wait between scrolls

});