showing confirmation before form submit php code example
Example 1: confirm before submit form php
onclick="return confirm('Are you sure you want to submit this form?')"
Example 2: click confirm before submit form php
<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>