Answers for "php onchange='this.form.submit() confirm"

confirm before submit form php

onclick="return confirm('Are you sure you want to submit this form?')"

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>