WordPress - Execute onclick function on button when page loads

Question

Background

I'm creating a registration page and want to run a function when the user presses the "Create Account" button. I have a button like this:

<button type="submit" name="wp-submit" onclick="register_process();" data-ppt-btn class ="mt-5">
<?php echo __("Create account"); ?>
</button>

Then I have the corresponding function in the same PHP file:

function register_process(){

    // Check the user type in the checkbox
    if(!jQuery("#user_type").is(':checked')){
     
        <?php
        
        // Header
        $headers = "MIME-Version: 1.0" . "\r\n";
        $headers = "Content-type:text/html;charset=UTF-8" . "\r\n";

        // Get user email
        $user_registration_email = "test987"; //$_POST['user_email'];

        // Recipients, subject and body of the email
        $admin_email_address = get_option('admin_email');
        $email_subject = "Test subject";
        $email_body = "Email: {$user_registration_email}";

        // send email
        wp_mail( $admin_email_address, $email_subject, $email_body, $headers);
        ?>
    }
}

Question

There are multiple issues, but the first is that the function "register_process" is running when I load the page, without even pressing the button. I read somewhere that the () should be removed from the onclick attribute and this solved the problem. However, nothing happens when the button is pressed.

I also tried checking if the user email field is empty and only sending the email if it is empty. However, this way I don't receive any emails at all.

Oddly enough, I have a few other things in my function, like checking if the input field is empty. These errors/warnings only fire when the button is pressed, and they look like this:

if(!jQuery("#privacypolicy").is(':checked')){
        jQuery("#ppt-form-error").addClass('text-danger mb-4').html("<?php echo __("You must accept our Privacy Policy to join our site .") ?>");
        CanContinue =0;
        return;
    }

How can I make the function only send the email when the button is pressed?

Answer 1

Onclick="register_process();" only needs to remove "();"