form.submit中控制。。。。
1<html>
2<script language="javascript">
3function dosubmit(){
4window.open('first.php?var1='+window.form.var1.value+'&var2='+window.form.var2.value);
5window.open('second.php?var1='+window.form.var1.value+'&var2='+window.form.var2.value);
6return false;
7}
8
9</script>
10<form name="form" onsubmit="return dosubmit();">
11<input name="var1" type="text"/><br/>
12<input name="var2" type="text"/>
13<br/><input type="submit"/></form></html>