The length property contains the number of Form objects that are in the forms[] array.
<html>
<form name="Form1">
<input type="button"
value="Green"
onClick = "document.bgColor='green'">
</form>
<form name="Form2">
<input type="button"
value="Blue"
onClick = "document.bgColor='blue'">
</form>
<script language="JavaScript">
<!--
document.write(document.forms.length," Form objects in document.");
-->
</script>
</html>