Convert ISO 8601 duration with JavaScript

Question

How can I convert duration with JavaScript, for example:

PT16H30M

Answer 1

You could theoretically get an ISO8601 Duration that looks like the following:

P1Y4M3W2DT10H31M3.452S

I wrote the following regular expression to parse this into groups:

(-)?P(?:([.,\d]+)Y)?(?:([.,\d]+)M)?(?:([.,\d]+)W)?(?:([.,\d]+)D)?T(?:([.,\d]+)H)?(?:([.,\d]+)M)?(?:([.,\d]+)S)?

It's not pretty, and someone better versed in regular expressions might be able to write a better one.

The groups boil down into the following:

1. Sign
2. Years
3. Months
4. Weeks
5. Days
6. Hours
7. Minutes
8. Seconds

I wrote the following function to convert it into a nice object:

var iso8601DurationRegex = /(-)?P(?:([.,\d]+)Y)?(?:([.,\d]+)M)?(?:([.,\d]+)W)?(?:([.,\d]+)D)?T(?:([.,\d]+)H)?(?:([.,\d]+)M)?(?:([.,\d]+)S)?/;

window.parseISO8601Duration = function (iso8601Duration) {
    var matches = iso8601Duration.match(iso8601DurationRegex);

    return {
        sign: matches[1] === undefined ? '+' : '-',
        years: matches[2] === undefined ? 0 : matches[2],
        months: matches[3] === undefined ? 0 : matches[3],
        weeks: matches[4] === undefined ? 0 : matches[4],
        days: matches[5] === undefined ? 0 : matches[5],
        hours: matches[6] === undefined ? 0 : matches[6],
        minutes: matches[7] === undefined ? 0 : matches[7],
        seconds: matches[8] === undefined ? 0 : matches[8]
    };
};

Used like this:

window.parseISO8601Duration('P1Y4M3W2DT10H31M3.452S');

Hope this helps someone out there.

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Update

If you are using momentjs, they have ISO8601 duration parsing functionality available. You'll need a plugin to format it, and it doesn't seem to handle durations that have weeks specified in the period as of the writing of this note.