function ChangeImg(id) {
 if (id == 'changeimg2') {
  document.getElementById(id).src="common/img/btn/2.jpg";
  document.getElementById(id).id="changeimg1";
 }

 if (id == 'changeimg1'){
  document.getElementById(id).src="common/img/btn/1.jpg";
  document.getElementById(id).id="changeimg2";
 }
}