As of today, ShareLaTeX has a built in PDF viewer based on PDF.js!
Why is this exciting?
Using our own PDF viewer gives us much control over the behaviour of the preview. The main benefit at the moment is that the preview will now stay in the same place when you recompile. Soon we’ll going even further and letting you jump between the same locations in the code and the preview.
Enabling the new PDF viewer for yourself
We’ll be rolling out the new viewer to everyone soon, but if you’d like to enjoy the benefits of it early, then you can enable it by going to your Account settings, and setting your PDF viewer to ‘built in’: