confirmar antes de enviar el formulario PHP
onclick="return confirm('Are you sure you want to submit this form?')"
SAIFUL ISLAM
onclick="return confirm('Are you sure you want to submit this form?')"<form action="adminprocess.php" method="POST" onsubmit="return confirm('Are you sure you want to submit this form?');">
<input type="submit" name="completeYes" value="Complete Transaction" />
</form>