Use "5 days ago (Tue)" if within the last week in moment.js

Question

I'm using moment.js.

The default for relative past days is "5 days ago". But what I want is that if it's within a week ago it should return "5 days ago (Tue)". If it's more than a week, I want the regular "5 days ago".

The docs say I can supply a function to custom format such a thing:

moment.locale('en', {
    relativeTime : {
        future: "in %s",
        past:   "%s ago",
        s:  "seconds",
        m:  "a minute",
        mm: "%d minutes",
        h:  "an hour",
        hh: "%d hours",
        //d:  "a day",   // this is the default
        d:  function(num, noSuffix, key, future) { return "a day (" + FOO + ")"; },
        //dd: "%d days", // this is the default
        dd: function(num, noSuffix, key, future) { return num + "days (" + FOO + ")"; },
        M:  "a month",
        MM: "%d months",
        y:  "a year",
        yy: "%d years"
    }
});

The problems are:

• How do I calculate the weekday name for variable FOO?
• It returns e.g. 5 days (Mon) ago instead of 5 days ago (Mon)
• I want this custom format only if it's <= 7 days (within the last week)

Answer 1

You can't manipulate the relative time format in the way you asked. However, you can simply do the comparison yourself to decide whether or not to append the additional string.

// your source moment
var m = moment("2015-06-04");

// calculate the number of whole days difference
var d = moment().diff(m,'days');

// create the output string
var s = m.fromNow() + (d >= 1 && d <= 7 ? m.format(" (ddd)") : "");