@Steve Farthing's answer is absolutely right.
But if you rotate more than 4 times then the image will get cropped from both the side. For that you need to do like this.
$("#clockwise").click(function(){
angleInDegrees+=90 % 360;
drawRotated(angleInDegrees);
if(angleInDegrees == 360){ // add this lines
angleInDegrees = 0
}
});
Then you will get the desired result. Thanks. Hope this will help someone :)