Use HTML5 canvas api

Canvas id will be my-canvas

Canvas backgound-color, height, and width should be rgb(0, 0, 0), 600px and 600px respectively.

tool-bar should have class name 'toolbar'.

tool-bar will have four different tools: line (id: 'line'), rectangle (id: 'rectangle'), circle (id: 'circle') and clear (id: 'clear').

Clear tool will clear complete canvas making the blackboard completely clean or blank.

tool-bar will have colors: white (id: 'white'), red (id: 'red'), blue (id: 'blue') and green (id: 'green').

Default color and tool for drawing will be red and line respectively.

While drawing curves(line/rectangle/circle), user should experience rubber-band effect.

Line tool shoud draw a line of selected color from mousedown location to mouseup.

Rectangle tool should draw a rectangle of selected color whose one cornor co-ordinates will be where user first mousedown and other conor(opposite to mousedown position) co-ordinates will be where user mouseup.

Circle tool should draw a circle of selected color whose center will be where user first mousedown and it's radius will be equal to distance between mousedown location and mouseup location.

User should able to draw curves in any direction.