>Field1 < input name=f1 > >Field2 < input name=f2 > >Sum < input name=f3 value=javascript:"return f1.value+f2.value;" > >How about something like this...
< script > function setf3value() { f3.value = parseInt(f1.value) + parseInt(f2.value) } < /script > Field1 < input name=f1 value = 0 onblur="setf3value()" > Field2 < input name=f2 value = 0 onblur="setf3value()" > Sum < input name=f3 value="" >