Código
<head> <script> var prog = 0; function change(){ ++prog; document.getElementById("progress").style.width=prog+"%"; } setInterval(change,100); </script> </head> <body> <table style="width:300px; height:20px;"> <tr> <td id="progress" style="background-color:red;width:25%;"></td> <td style="background-color:yellow;"></td> </tr> </table> </body>