JavaScriptのtoLocaleStringについて

let today = new Date()
today.toLocaleString(locales, options)

{
    hour12:[true,false],
    era:["narrow","short","long"],
    year:["numeric","2-digit"],
    month:["numeric","2-digit","narrow","short","long"],
    day:["numeric","2-digit"],
    weekday:["narrow","short","long"],
    hour:["numeric","2-digit"],
    minute:["numeric","2-digit"],
    second:["numeric","2-digit"],
    timeZoneName:["short","long"]
    timeZone:["foo/bar"]
}