You can always format a date by extracting the parts and combine them using string functions in desired order:

function formatDate(date) {
  let datePart = [
    date.getMonth() + 1,
    date.getDate(),
    date.getFullYear()
  ].map((n, i) => n.toString().padStart(i === 2 ? 4 : 2, "0")).join("/");
  let timePart = [
    date.getHours(),
    date.getMinutes(),
    date.getSeconds()
  ].map((n, i) => n.toString().padStart(2, "0")).join(":");
  return datePart + " " + timePart;
}

let date = new Date();
console.log("%o => %s", date, formatDate(date));

Use below function in fiddle

     <a href="https://jsfiddle.net/pareshmutha1900/mbcmf0k4/">Link</a>

     var dateFormat = function () {
            var    token = /d{1,4}|m{1,4}|yy(?:yy)?|([HhMsTt])\1?|[LloSZ]|"[^"]*"|'[^']*'/g,
                timezone = /\b(?:[PMCEA][SDP]T|(?:Pacific|Mountain|Central|Eastern|Atlantic) (?:Standard|Daylight|Prevailing) Time|(?:GMT|UTC)(?:[-+]\d{4})?)\b/g,
                timezoneClip = /[^-+\dA-Z]/g,
                pad = function (val, len) {
                    val = String(val);
                    len = len || 2;
                    while (val.length < len) val = "0" + val;
                    return val;
                };

            // Regexes and supporting functions are cached through closure
            return function (date, mask, utc) {
                var dF = dateFormat;

                // You can't provide utc if you skip other args (use the "UTC:" mask prefix)
                if (arguments.length == 1 && Object.prototype.toString.call(date) == "[object String]" && !/\d/.test(date)) {
                    mask = date;
                    date = undefined;
                }

                // Passing date through Date applies Date.parse, if necessary
                date = date ? new Date(date) : new Date;
                if (isNaN(date)) throw SyntaxError("invalid date");

                mask = String(dF.masks[mask] || mask || dF.masks["default"]);

                // Allow setting the utc argument via the mask
                if (mask.slice(0, 4) == "UTC:") {
                    mask = mask.slice(4);
                    utc = true;
                }

                var    _ = utc ? "getUTC" : "get",
                    d = date[_ + "Date"](),
                    D = date[_ + "Day"](),
                    m = date[_ + "Month"](),
                    y = date[_ + "FullYear"](),
                    H = date[_ + "Hours"](),
                    M = date[_ + "Minutes"](),
                    s = date[_ + "Seconds"](),
                    L = date[_ + "Milliseconds"](),
                    o = utc ? 0 : date.getTimezoneOffset(),
                    flags = {
                        d:    d,
                        dd:   pad(d),
                        ddd:  dF.i18n.dayNames[D],
                        dddd: dF.i18n.dayNames[D + 7],
                        m:    m + 1,
                        mm:   pad(m + 1),
                        mmm:  dF.i18n.monthNames[m],
                        mmmm: dF.i18n.monthNames[m + 12],
                        yy:   String(y).slice(2),
                        yyyy: y,
                        h:    H % 12 || 12,
                        hh:   pad(H % 12 || 12),
                        H:    H,
                        HH:   pad(H),
                        M:    M,
                        MM:   pad(M),
                        s:    s,
                        ss:   pad(s),
                        l:    pad(L, 3),
                        L:    pad(L > 99 ? Math.round(L / 10) : L),
                        t:    H < 12 ? "a"  : "p",
                        tt:   H < 12 ? "am" : "pm",
                        T:    H < 12 ? "A"  : "P",
                        TT:   H < 12 ? "AM" : "PM",
                        Z:    utc ? "UTC" : (String(date).match(timezone) || [""]).pop().replace(timezoneClip, ""),
                        o:    (o > 0 ? "-" : "+") + pad(Math.floor(Math.abs(o) / 60) * 100 + Math.abs(o) % 60, 4),
                        S:    ["th", "st", "nd", "rd"][d % 10 > 3 ? 0 : (d % 100 - d % 10 != 10) * d % 10]
                    };

                return mask.replace(token, function ($0) {
                    return $0 in flags ? flags[0.slice(1, $0.length - 1);
                });
            };
        }();

        // Some common format strings
        dateFormat.masks = {
            "default":      "ddd mmm dd yyyy HH:MM:ss",
            shortDate:      "m/d/yy",
            mediumDate:     "mmm d, yyyy",
            longDate:       "mmmm d, yyyy",
            fullDate:       "dddd, mmmm d, yyyy",
            shortTime:      "h:MM TT",
            mediumTime:     "h:MM:ss TT",
            longTime:       "h:MM:ss TT Z",
            isoDate:        "yyyy-mm-dd",
            isoTime:        "HH:MM:ss",
            isoDateTime:    "yyyy-mm-dd'T'HH:MM:ss",
            isoUtcDateTime: "UTC:yyyy-mm-dd'T'HH:MM:ss'Z'"
        };

        // Internationalization strings
        dateFormat.i18n = {
            dayNames: [
                "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
                "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"
            ],
            monthNames: [
                "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec",
                "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"
            ]
        };

        // For convenience...
        Date.prototype.format = function (mask, utc) {
            return dateFormat(this, mask, utc);
        };





    today = new Date();
    var dateString = today.format("yyyy-mm-dd h:mm");
    alert(dateString);

The JavaScript Intl.DateTimeFormat method provides a convenient way to format dates.

Here is how the needed format can be constructed:

const date = new Date("2010-08-10");

let d=new Intl.DateTimeFormat('en-GB',{year:"numeric", month:"short",day:"2-digit"}).format(date).split(" ").join("-");

console.log(d);

You can do:

function formatDate(date) {
    var d = new Date(date),
        month = '' + (d.getMonth() + 1),
        day = '' + d.getDate(),
        year = d.getFullYear();

    if (month.length < 2) 
        month = '0' + month;
    if (day.length < 2) 
        day = '0' + day;

    return [year, month, day].join('-');
}
 
console.log(formatDate('Sun May 11,2014'));

Usage example:

console.log(formatDate('Sun May 11,2014'));

Output:

2014-05-11

Demo on JSFiddle: http://jsfiddle.net/abdulrauf6182012/2Frm3/

It's indicated by an f:

"dd/MM/yyyy HH:mm:ss fff"