JSFiddle - React, Tailwind, and code Playground

JavaScript

function addDays(myDate,days) {
    return new Date(myDate.getTime() + days*24*60*60*1000);
}

function subtractDays(myDate,days) {
    return new Date(myDate.getTime() - days*24*60*60*1000);
}

function dateOfNext(weekdayNumber) {
    var today = new Date();

    var lastSunday = subtractDays(today, today.getDay());

    var daysToAdd = weekdayNumber;
    if (weekdayNumber <= today.getDay()) {
        daysToAdd = daysToAdd + 7;
    }

    return addDays(lastSunday, daysToAdd);
}

var nextWednesday = dateOfNext(5);
alert(nextWednesday.toDateString());