get timezone string

tz.js

function getTimeZoneString() {
    var abbr = "";

    try {
        abbr = new Intl.DateTimeFormat().resolvedOptions().timeZone;
    } catch (e) {
        abbr = ""
    }

    return abbr || "";
}

// with options

function getTimeZoneStr() {
    var abbr = "";

    try {
        abbr = new Intl.DateTimeFormat('en-US', {
            hour: 'numeric',
            hour12: false,
            timeZoneName: "long"
        }).resolvedOptions().timeZone;
    } catch (e) {
        abbr = ""
    }

    return abbr || "";
}