<form>
  <!--当点击相应按钮，执行相应操作，为按钮添加相应事件-->
    <input type="button" value="改变颜色" onClick="1()">  
    <input type="button" value="改变宽高" onClick="2()">
    <input type="button" value="隐藏内容" onClick="3()">
    <input type="button" value="显示内容" onClick="4()">
    <input type="button" value="取消设置" onClick="5()">
  </form>
  <script type="text/javascript">
    var txt=document.getElementById("txt");
        function 1()
        {
            txt.style.color="red";
            txt.style.backgroundColor="#ccc";
        }
        function 2()
        {
            txt.style.width="300px";
            txt.style.height="300px";
        }
        function 3()
        {
            txt.style.display="none";
        }
        function 4()
        {
            txt.style.display="block";
        }
        function 5()
        {
            var a=confirm();
            if(a==true)
            {
                txt.removeAttribute("style");
            }
        }
  </script>