Can we use OpenCV from Javascript? Is there such implementation?
Is there any JS libraries that can be used for detecting face elements in the picture or video?
I don't think there is any way of using openCV in JS other than communicating with a server with openCV on it and doing the processing there.
There is one Face detection algo in JS that I know of: http://badassjs.com/post/1461943420/face-detection-in-javascript-via-html5-canvas