Uncaught TypeError checkboxChange is not a function

[patrmich]

Hi,

My shop is built with Prestahsop 1.5.6.2

In the browser console, js tab, I can see the following error :
cart-summary.js:835 Uncaught TypeError: $(...).checkboxChange is not a function
    at HTMLDocument.<anonymous> (../js/cart-summary.js:835)
    at o (../xxxxxxxxxxxxx.js:2)
    at Object.fireWith (../xxxxxxxxxxxxx.js:2)   
    at Function.ready (../xxxxxxxxxxxxx.js:2)
    at HTMLDocument.B (../xxxxxxxxxxxxx.js:2)

The line 835 to 843 of the js/cart-summary.js file are the following :

    $('#gift').checkboxChange(function() { $('#gift_div').show('slow'); }, function() { $('#gift_div').hide('slow'); });
    $('#enable-multishipping').checkboxChange(
        function() {
            $('.standard-checkout').hide(0);
            $('.multishipping-checkout').show(0);
        },
        function() {
            $('.standard-checkout').show(0);
            $('.multishipping-checkout').hide(0);

Such error only displays on category and product-list pages, but not on product pages.

1- Would you know what is the purpose of the checkboxChange function ?

2- How to avoid this error ?

I thank you in advance for any reply.

Patrick

[NemoPS]

It's odd it displays on category pages actually, it should only trigger in the checkout. Anyway that's not a core jquery function, it must be some plugin (though google doesn't seem to know it?) or something made by the theme developer. Is it a paid theme?