function chksearchtext(search_form){
    search_form.keywords.value=trim(search_form.keywords.value);
	if (search_form.keywords.value.length < 2 )	{
		alert('Termini di ricerca troppo brevi. (minimo 2 caratteri)') ;
		search_form.keywords.focus();
		return (false);
	}

	if (search_form.keywords.value == 'Ricerca' ){
		alert('Inserire un termine di ricerca.');
		search_form.keywords.focus();
		return (false);
	}

	if (search_form.keywords.value.length > 50 ){
		alert('Termini di ricerca troppo lunghi. (massimo 50 caratteri)');
		search_form.keywords.focus();
		return (false);
	}

	return true;
}
function trim (str) {
	var	str = str.replace(/^\s\s*/, ''),
		ws = /\s/,
		i = str.length;
	while (ws.test(str.charAt(--i)));
	return str.slice(0, i + 1);
}