Visualization researchers perform user studies to evaluate the ef- fectiveness and usability of produced visualisations. While there are different styles of evaluation, some popular techniques involve comparing the result of several parameter changes, looking how re- sults have changed and if a change is noticeable. Developers need to display many different pictures, to a wide variety of users, while guaranteeing full coverage of all potential designs across all par- ticipants. One solution is to use static screen shots of their outputs along with popular on line surveying tools, but such a solution omits any system interactivity. Alternatively they can create their own surveying application on a chosen platform. We introduce VisSur- vey.js, a JavaScript library that helps developers create evaluation studies. Developers can create user studies of their application in a web browser, and easily capture the results.