获取文本框的值而不提交表单并将其分配给隐藏字段

Question

在下面的代码中，我需要将firstname的值传递给隐藏字段（billing_name）。我已经尝试过使用jQuery和PHP。但它没有解决。

任何人帮助我通过文本框的值，而形式提交到隐藏字段

<form method="POST" name="customerData" action="<?php echo get_template_directory_uri(); ?>/payment/ccavRequestHandler.php"> 
<div id="personal-reservation-form-wrap"> 
<h5><?php echo $personalInfoHeader; ?></h5> 
<div id="required-desc"><?php echo $personalInfoDescription; ?></div> 

<div id="resform-firstname" class="form-field-wrap"> 
<div class="resform-header"><?php _e("Full Name","nation") ?> <span class="main-reservation-form-asterisk">*</span></div> 
<input type="text" name="firstname" class="form-field-wrap required-field" id="firstname" required > 
</div> 

<div id="resform-lastname" class="form-field-wrap"> 
<div class="resform-header"><?php _e("Mobile Number","nation") ?> <span class="main-reservation-form-asterisk">*</span></div> 
<input type="text" name="lastname" class="form-field-wrap required-field" required> 
</div> 

<div id="resform-email" class="form-field-wrap"> 
<div class="resform-header"><?php _e("Email","nation") ?> <span class="main-reservation-form-asterisk">*</span></div> 
<input type="text" name="email" class="form-field-wrap required-field email-field" required> 
</div> 

<div id="resform-retypeyouremail" class="form-field-wrap"> 
<div class="resform-header"><?php _e("Address","nation") ?> <span class="main-reservation-form-asterisk">*</span></div> 
<input type="text" name="resform-retypeyouremail" class="form-field-wrap required-field email-field" required> 
</div> 

<input type="hidden" name="order_id" value="<?php echo $tnx1 ?>"/> 
<input type="hidden" name="merchant_id" value="555555"/> 
<input type="hidden" name="amount" value="<?php echo $total_money; ?>"/> 
<input type="hidden" name="checkin" value="<?php echo $checkin1; ?>"/> 
<input type="hidden" name="checkout" value="<?php echo $checkout1; ?>"/> 
<input type="hidden" name="roomid" value="<?php echo $room_id ?>"/> 
<input type="hidden" name="currency" value="INR"/> 
<input type="hidden" name="room_id" value="<?php echo $room_id; ?>" />      

<input type="hidden" name="billing_name" value=""> 
<input type="hidden" name="billing_email" value=""> 
<input type="hidden" name="billing_tel" value=""> 
<input type="hidden" name="billing_address" value=""> 
<input type="hidden" name="redirect_url" value="http://hotels.com/wp-content/themes/wpnation/payment/ccavResponseHandler.php"> 
<input type="hidden" name="cancel_url" value="http://hotels.com/wp-content/themes/wpnation/payment/ccavResponseHandler.php"/> 

<div id="resform-comments" class="form-field-wrap"> 
<div class="resform-header"><?php _e("Comments","nation") ?></div> 
<textarea type="text" name="resform-comments" required></textarea> 
</div> 

<?php if ($enable_coupon) { ?> 
<div id="resform-firstname" class="form-field-wrap"> 
<div class="resform-header"><?php _e("Enter Coupon Name","nation") ?></div> 
<input type="text" name="resform-coupon" class="form-field-wrap"> 
</div> 
<?php } ?> 

<input name="room-id" type="hidden" value="<?php echo $_POST["room-id"]; ?>"> 

<input name="step3-send" type="hidden" value="true"> 
</div> 

Answer 1

如果提交后，可以填补这样的：

<input type="hidden" name="text_hidden" value="<?php echo htmlspecialchars($_POST['text_visible']); ?>"> 

如果在飞行中，然后使用jQuery：

<script> 
$(document).ready(function() { 
    $('input[name="text_visible"]').on('change', function() { 
     $('input[name="text_hidden"]').val($('input[name="text_visible"]').val()); 
    }); 
}); 
</script> 

把这个漂亮的地方，我会建议之前或之后的形式