Here is an example of rendering a pdf

pdf.js

phantom = require('phantom')
phantom.create(function(ph) {
   ph.createPage(function(page) {
     page.open("http://www.google.com", function(status) {
        page.render('google.pdf', function(){
        console.log('Page Rendered');
        ph.exit();
      });
    });
  });
});