def add_javascripts(self, *js_files):
        """add javascripts files in HTML body"""
        # create the script tag if don't exists
        if self.main_soup.script is None:
            script_tag = self.main_soup.new_tag('script')
            self.main_soup.body.append(script_tag)

        for js_file in js_files:
            self.main_soup.script.append(self._text_file(js_file))