The with statement takes an object and refers to all of the properties, methods, and events of that object without directly referencing the object itself.
<html>
<script language="JavaScript">
<!--
var myNum = 25;
var myE, mySin, mySqrt;
with (Math) {
myE = E;
mySqrt = sqrt(myNum)
document.writeln(mySqrt);
mySin = sin(PI/myNum);
document.write(mySin);
}
-->
</script>
</html>