I am building a site in node.js that allows users to have a custom page that can be edited in a dashboard. I would like this dashboard to have a live preview (similar to the way Shopify does it) in an iframe, where every time the user makes changes, the preview updates with their changes (i.e. background image or header text). The options are saved in the users document in my mongodb database, and rendered via Liquid. What is the best approach to achieve this? Should I store their options in a temporary json file? Thanks!