call a javascript function if a required field validator fails

I have a validation summary control which is hidden so when Page.IsValid != true i show the icon to view validation summary control, it works fine for server side validation. No i have implemented required field validator in web form and it is working properly but i get error message displayed only next to control to valdate control (eg textbox) and as the validation summary is hidden. Is there a way when required field validator fails i can call JavaScript function to show validation summary control.

 Thanks
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