formatting-function.js

const fullFormat = new Intl.DateTimeFormat("en", { dateStyle: "full" });

const ordinalSuffixes = {
    "one": "st",
    "two": "nd",
    "few": "rd",
    "other": "th"
};

const ordinalPluralRules = new Intl.PluralRules("en", { type: "ordinal" });

function withOrdinalSuffix(x) {
    if(typeof x != "number") throw new TypeError(`Expected Number but received ${typeof x}`);
    if(x < 1) throw new RangeError(`Expected a number > 0 but received ${x}`);
    const ordinal = ordinalPluralRules.select(x);
    if (!ordinal in ordinalSuffixes) throw new Error(`Unexpected ordinal ${ordinal}`);
    const suffix = ordinalSuffixes[ordinal];
    return `${x}${suffix}`;
}

const now = new Date();
const parts = fullFormat.formatToParts(now);

const weekDayName = parts.find(p => p.type === "weekday").value;
const dayName = parts.find(p => p.type === "day").value;

const dayWithSuffix = withOrdinalSuffix(Number(dayName));

`${weekDayName} ${dayWithSuffix}` // Thursday 28th