Click and Point on HTML5 to interact with Unity Game?

How do I make a game and connect it by WebSockets or what have you to a web browser? For example, lets say I have a game that is escape the room, and I want to be able to have someone go to a link and play the game just by clicking on the screen. I don't want to export the whole game just have a video of it running and then detect where the person is clicking on the screen to convert it to game coordinates to send to Unity from HTML5?