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Paypal - User-Defined Dollar Amount

I am trying to get a Paypal button to accept the input from the user as the dollar amount to be billed. This is for a bill payment option that allows the user to put in their invoice number and invoice amount, as each user's total will likely be different.

I assigned IDs to the relevant fields. The main thing that I am needing help with is the JavaScript. I am not certain that I have it right.

I need it to:

  • select the value that the user enters
  • feed that value into the Paypal value amount (initially set at $4.00)
  • update on user input keyup event
  • successfully submit to Paypal

Here is the code:

<form action="https://www.paypal.com/cgi-bin/webscr" method="post" target="_top"> <input type="hidden" name="cmd" value="_xclick"> <input type="hidden" name="business" value=busn@domain.com"> <input type="hidden" name="lc" value="US"> <input type="hidden" name="item_name" value="Bill Payment"> <input type="hidden" name="amount" id="payAMT" value="4.00"> <input type="hidden" name="currency_code" value="USD"> <input type="hidden" name="button_subtype" value="services"> <input type="hidden" name="no_note" value="0"> <input type="hidden" name="bn" value="PP-BuyNowBF:btn_paynowCC_LG.gif:NonHostedGuest"> <table> <tr> <td> <input type="hidden" name="on0" value="Invoice Number:">Invoice Number: </td> </tr> <tr> <td> <input type="text" name="os0" maxlength="200"> </td> </tr> <tr> <td> <input type="hidden" name="on1" value="Amount:">Amount: </td> </tr> <tr> <td> <input type="text" name="os1" id="valInput" maxlength="200"> </td> </tr> </table> <input type="image" src="https://www.paypalobjects.com/en_US/i/btn/btn_paynowCC_LG.gif" border="0" name="submit" alt="PayPal - The safer, easier way to pay online!"> <img alt="" border="0" src="https://www.paypalobjects.com/en_US/i/scr/pixel.gif" width="1" height="1"> </form>

        var $sendAmount = $("#payAMT");
        var $userAmount = $("#valInput").val();

        function $updateAmount( $sendAmount ) {
            $sendAmount.attr(value, $userAmount).keyup();

1 Answer

Hey Joshua! I have edited your JS into something that does what I believe you are trying to do:

    var $sendAmount = $("#payAMT");
    var $userAmount = $("#valInput");

    // When a keyup event occurs while #valInput is active...
        // Set the value of #payAMT to equal the value of #valInput
        $sendAmount.val( $(this).val() );

I also noticed that you are missing some quotation marks when you declared the value for the business input.

If you have any questions about that jQuery code, let me know! :D

Thanks Erik, I believe that this is exactly what I was looking for!

Update, there was just one extra thing that this needed, the .append(). This was the final code that I used:

    var $sendAmount = $("#payAMT");
    var $userAmount = $("#valInput");

    // When a keyup event occurs while #valInput is active...
        // Set the value of #payAMT to equal the value of #valInput
        $sendAmount.append().val( $(this).val() );

Append will not do anything if you do not pass it an argument, but I am also pretty sure you do not need or want it in this situation :P