Inserting html div value in js var

I have the following code at bottom of page to update amount (p_amount) and package id (pack_id) (all codes are in same page)

       jQuery.ajax({                    
        url : ajaxurl,                   
        dataType : "json",
        type : "post",
        data : search_params,
        success : function(response){
            if(response.code=='success'){                           
                jQuery('#coupon-result').html('<img src="<?php echo WP_iv_membership_URLPATH; ?>admin/files/images/right_icon.png">');
            }else{
                    jQuery('#coupon-result').html('<img src="<?php echo   WP_iv_membership_URLPATH; ?>admin/files/images/wrong_16x16.png">');
            }
            jQuery('#p_amount').html(response.p_amount);

                }

after this, It updates the value here

    <div class="col-md-8 col-xs-8 col-sm-8 " id="p_amount">     

and here in the middle of page i am using js to send values over my payment gateway provider, I want to insert the updated value of amount(p_amount) inside (var amount), but it never updates

 <div class="checkout">    
  <script type="text/javascript">
    var amount       = 'p_amount';
    var currency     = 'USD';