// From 2.12.0 onward moment.updateLocale('en', { weekdaysMin : String[] }); moment.updateLocale('en', { weekdaysMin : Function });

// From 2.8.1 to 2.11.2 moment.locale('en', { longDateFormat : Object });

// Deprecated in 2.8.1 moment.lang('en', { longDateFormat : Object });

---

Locale#longDateFormat should be an object containing a key/value pair for each long date format L LL LLL LLLL LT LTS. LT should be the time format, and is also used for moment#calendar.

moment.updateLocale('en', {
    longDateFormat : {
        LT: "h:mm A",
        LTS: "h:mm:ss A",
        L: "MM/DD/YYYY",
        l: "M/D/YYYY",
        LL: "MMMM Do YYYY",
        ll: "MMM D YYYY",
        LLL: "MMMM Do YYYY LT",
        lll: "MMM D YYYY LT",
        LLLL: "dddd, MMMM Do YYYY LT",
        llll: "ddd, MMM D YYYY LT"
    }
});

You can eliminate the lowercase l tokens and they will be created automatically by replacing long tokens with the short token variants.

moment.updateLocale('en', {
    longDateFormat : {
        LT: "h:mm A",
        LTS: "h:mm:ss A",
        L: "MM/DD/YYYY",
        LL: "MMMM Do YYYY",
        LLL: "MMMM Do YYYY LT",
        LLLL: "dddd, MMMM Do YYYY LT"
    }
});