Animate cc html5 find original canvas height and width

I'm looking for a way to get the canvas width and height after having opened the page and posibly resized the page.

My publish settings have to be on responsive but I need to get the widht and height my canvas was when it was drawn. If I after opening the page and resizing it simply get the width/height of the canvas by looking at it's current state this won't give me the initial values of width and height but it will return the current height and width.

I need to know the width and height it is when its not resized when it's currently resized to place an object on the mouse location after click and for this i need to calculate the ratio between the original size of the canvas and the current size. I can't add the width and the height of my drawing to my script because the width and height can be different and i would like to not have to edit the script each time.