13点击按钮切换图片

<input type="button" id="btn11">
        <img src="../logo3.png" id="imm">
        <script type="text/javascript">
            function my$(id) {
                return document.getElementById(id);
            }
            my$("btn11").onclick=function(){
                my$("imm").src="../logo2.jpg";
            }
        </script>