Trying to add help text in Coupon code field

I want to add some descriptive text on the promo code field that says "enter your promo code!", so firstly i added a new define to includes/languages/english/modules/order_total/ot_coupon.php

define('CODE_SUBMIT_DEFAULT_TEXT','enter your promo code!');

I then changed line 137 of includes/modules/order_total/ot_coupon.php from

'field' => zen_draw_input_field('dc_redeem_code', '', 'id="disc-' . $this->code . '" onkeyup="submitFunction(0,0)"'),

to

'field' => zen_draw_input_field('dc_redeem_code', '', 'id="disc-' . $this->code . '" onkeyup="submitFunction(0,0)" class="promo-code-box" value="' . CODE_SUBMIT_DEFAULT_TEXT . '" onfocus="if (this.value == '' . CODE_SUBMIT_DEFAULT_TEXT . '') this.value = '';" onblur="if (this.value == '') this.value = '' . CODE_SUBMIT_DEFAULT_TEXT . '';"'),

followed by changing line 158 from

if ((isset($_POST['dc_redeem_code']) && $_POST['dc_redeem_code'] != '') || (isset($discount_coupon->fields['coupon_code']) && $discount_coupon->fields['coupon_code'] != '')) {

to

if ((isset($_POST['dc_redeem_code']) && $_POST['dc_redeem_code'] != '' && ($_POST['dc_redeem_code'] != CODE_SUBMIT_DEFAULT_TEXT)) || (isset($discount_coupon->fields['coupon_code']) && $discount_coupon->fields['coupon_code'] != '')) {

The problem I have is that when I click the Continue button, checkout does not move to the next step. If I remove the edit from line 158, I get the message stack warning to say that the coupon code is invalid due to the value of CODE_SUBMIT_DEFAULT_TEXT being stored.

Looking at the code, I thought that the if statement at line 158 was what was checking for a blank field, i.e. no coupon code present, and so telling it to ignore the entry if it matched the define would be sufficient. Obviously not.

Any suggestions on what else might be amiss here?

Nobody got any ideas on this?

You could use the HTML5 "placeholder" attribute instead of the old approach of injecting a bunch of javascript which might have a mismatched set of quotation marks thus causing your form to break.
Most modern browsers support the HTML5 placeholder markup even on non-HTML5 templates, so this should work for most visitors.

Thus, this:
'field' => zen_draw_input_field('dc_redeem_code', '', 'id="disc-' . $this->code . '" onkeyup="submitFunction(0,0)"'),

could become something like this:

'field' => zen_draw_input_field('dc_redeem_code', '', 'id="disc-' . $this->code . '" onkeyup="submitFunction(0,0)" placeholder="' . addslashes(CODE_SUBMIT_DEFAULT_TEXT) . '" '),

I did look at "placeholder" DrByte, but when I tried it the text stayed visible on the input field even after entering a coupon code. Whether that was due to an error, or the way "placeholder" works, I don't know.

strelitzia:

The problem I have is that when I click the Continue button, checkout does not move to the next step.
That happens when the generated HTML isn't fully valid ... which is typically caused by mismatched single-quotes or double-quotes (which could be inside your language-constant), or extra/missing < or > symbols. (Or nesting forms inside each other, which I'm pretty sure isn't what you're doing here.)

Running the page source (right-click, choose View Page Source) through an HTML validator to show you which HTML tags are incorrect is a good starting point.