src/Buttons/BetterButton_Delete.php
public function baseTransform()
    {
        parent::baseTransform();
        Requirements::javascript(BETTER_BUTTONS_DIR.'/javascript/gridfield_betterbuttons_delete.js');

        return $this
            ->setUseButtonTag(true)
            ->addExtraClass('btn-danger-outline btn-hide-outline font-icon-trash-bin gridfield-better-buttons-delete')
            ->setAttribute("data-toggletext", _t('GridFieldBetterButtons.AREYOUSURE', 'Yes. Delete this item.'))
            ->setAttribute("data-confirmtext", _t('GridFieldDetailForm.CANCELDELETE', 'No. Don\'t delete.'));
    }
public function baseTransform()
    {
        parent::baseTransform();
        Requirements::javascript(BETTER_BUTTONS_DIR.'/javascript/gridfield_betterbuttons_delete.js');

        return $this
            ->setUseButtonTag(true)
            ->addExtraClass('btn-danger-outline btn-hide-outline font-icon-trash-bin gridfield-better-buttons-delete')
            ->setAttribute("data-toggletext", _t('GridFieldBetterButtons.AREYOUSURE', 'Yes. Delete this item.'))
            ->setAttribute("data-confirmtext", _t('GridFieldDetailForm.CANCELDELETE', 'No. Don\'t delete.'));
    }
Adds the JS, sets up necessary HTML attributes
@return FormAction