window.onload = choosePic;

var myPix = new 
Array("assets/images/sidebar0.jpg","assets/images/sidebar1.jpg","assets/images/sidebar2.jpg","assets/images/sidebar3.jpg","assets/images/sidebar4.jpg","assets/images/sidebar5.jpg","assets/images/sidebar6.jpg","assets/images/sidebar7.jpg","assets/images/sidebar8.jpg","assets/images/sidebar9.jpg");

function choosePic() {
	randomNum = Math.floor((Math.random() * myPix.length));
	document.getElementById("myPicture").src = myPix[randomNum];
}