[nikita.mmf]

function pluralForm ( n, forms ) {
    return forms[(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2) ];
}
//pluralForm( 1, ["стул", "стула", "стульев"] );