Enable Command Button on entering all values in mandatory fields

.Next Button should be enabled only when all required fields have been selected or filled.

Can any one help me out with this,
I have written javascript on onchange of textfields, but now i have too many mandatory fields, how it can be done using "Rendered" attribute and also disabled="true" is creating problem as not passing the value to next page.

Thanks in adv

Unfortunately, you need javascript.

The rendered attribute is applied when the page reloads and is redrawn by the server, so you'd actually have to make a server request (which is what the commmand button does anyway).

When set by the server, I've had problems with the disabled attribute. On one program, I could re-enable the control with client-side javascript, but since the page had been rendered with a disabled control, it didn't have the extra support that a fully-enabled control would have, even though I had enabled the HTML control itself.

Thanks Tim

The Same has been done using Javascript