<input type="button" value="改变颜色" onclick="changecolor()">  

    <input type="button" value="改变宽高" >

    <input type="button" value="隐藏内容" >

    <input type="button" value="显示内容" >

    <input type="button" value="取消设置" >

  </form>

  <script type="text/javascript">

  var txt=document.getElementById("txt");

    function:changecolor()

     {

         txt.style.color="red";

         txt.style.backgroundColor="#ccc";

     }