Where is located "bundle.changeSelection" from "select.phtml"?

Question

I'm looking for a file containing the javascript function called in the following file from Magento 1.4.1.1. I would like to add custom codes.

var\www\app\design\frontend\interface_lpf_fr\theme_lpf\template\bundle\catalog\product\view\type\bundle\option\select.phtml

...
    <select onchange="bundle.changeSelection(this)" id="bundle-option-<?php echo $_option->getId() ?>" name="bundle_option[<?php echo $_option->getId() ?>]" class="bundle-option-<?php echo $_option->getId() ?><?php if ($_option->getRequired()) echo ' required-entry' ?> bundle-option-select">
        <option value=""><?php echo $this->__('Choose a selection...') ?></option>
        <?php $i=0; ?>
        <?php foreach($_selections as $_selection): ?>
            <option value="<?php echo $_selection->getSelectionId() ?>"<?php echo ($_selection->getIsDefault() && $_selection->isSaleable())?' selected="selected" ':'' ?><?php echo !$_selection->isSaleable()?' disabled="disabled" ':'' ?>><?php echo $this->getSelectionTitlePrice($_selection, false) ?></option>
        <?php endforeach;?>
    </select>
...

Answer 1

Try in var\www\skin\frontend\interface_lpf_fr\theme_lpf\js\bundle.js. If there is no such file try var\www\skin\frontend\interface_lpf_fr\default\js\bundle.js and finally var\www\skin\frontend\base\default\js\bundle.js.