You are required to create a to-do-list in JavaScript based. This application must cover basic features, such as add, edit and remove an item from the list. Upon adding an item, user can define the priority of it. There are three different levels of priorities, which are high, medium and low priorities. Each item must be arranged according to the periority set. For an example, all the items that set in high priority must be placed on top of the list. The design and outlook of the list is based on your creativity, for instance, you may use three colours to differentiate the different level of priority. You are allowed to use any external open source library (with proper citation and acknowledgment required) in order to enhance the visual effect or to achieve something needed for your application. You are also encouraged to add any extra feature that suit the need of your application for rewarding some bonus marks. Please answer as the requirements need.