How to save multiple images captured from webcam to disk

I wanted to capture and save images from webcam when a certain trigger goes live. I am using html5's getusermedia method to display and capture an image from the webcam. Now, I want to save those images to a directory on disk directly without the browser prompt with it's time of capture being its name. Is there any way to do that? I do understand that I can save a canvas but I do not want to replace the same image as I want multiple images to be saved in the directory wrt time.