with的使用

 <script>

var str="javascript";

var num =1234;

with(document)

{

  writeln(str.toUpperCase()+"<br/>");

  write(str.toString().charAt(2),"<br/>");

  write(str.substring(0,4),"<br/>");

}

</script>

<script>

with(document)

{

  write(screen.availHeight,"<br>");

  write(screen.availWidth),"<br>");

  write(screen.availHeight,"<br>")

}

</script>