This line of javascript is in the Magento base code in app/design/frontend/base/default/template/persistent/checkout/onepage/billing.phtml:

        $('billing-address-select') && billing.newAddress(!$('billing-address-select').value);

Here is the line in context:

    <script type="text/javascript">
var billing = new Billing('co-billing-form', 
                          '<?php echo $this->getUrl('checkout/onepage/getAddress') ?>address/', 
                          '<?php echo $this->getUrl('checkout/onepage/saveBilling') ?>');
var billingForm = new VarienForm('co-billing-form');

                                  '<?php echo $this->getUrl('directory/json/childRegion') ?>', 
                                  '<?php echo $this->__('Select State/Province...') ?>');*/

$('billing-address-select') && billing.newAddress(!$('billing-address-select').value);

var billingRegionUpdater = new RegionUpdater('billing:country_id', 
                                             <?php echo $this->helper('directory')->getRegionJson() ?>, 
if ($('onepage-guest-register-button')) {
    Event.observe($('onepage-guest-register-button'), 'click', function(event) {
        var billingRememberMe = $('co-billing-form').select('#remember-me-box');
        if (billingRememberMe.length > 0) {
            if ($('login:guest') && $('login:guest').checked) {
            } else if ($('login:register') && ($('login:register').checked || $('login:register').type == 'hidden')) {

It looks like it's comparing two values but doing nothing with the comparison. What is the purpose of it?

  • Did you try to paste it into the console of the developers tool of your browser and see what it returns? – Akif Apr 2 '15 at 19:22
  • It returns "undefined". I tested while on one page checkout using persistent billing. I verified that billing.phtml is present by turning on the template outlines in the admin panel's developer tools. – Reflexorozy Apr 2 '15 at 20:06

I did some research on this. I thought the && was a purely logical "and", but it can also be used as a shortcut for "if then".

In this case, if $('billing-address-select') is true, the newAddress function (in opcheckout.js) will be called with "!$('billing-address-select').value" as an argument. It's a weird way to programmatically show or hide the new address form on one page checkout.

Here's a Stack Overflow question where this is explained: https://stackoverflow.com/questions/3859433/an-explanation-of-shorthand-in-javascript

And a good explanation of & vs &&: https://stackoverflow.com/questions/7310109/whats-the-difference-between-and-in-javascript

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