A way to render an elapsed period of time in humanized form. The proposed API is:

Javascript:

var date1;
var date2;

// a field with days, hours, minutes and seconds
var duration = (date1.getTime() - date2.getTime()).toDuration();

// a string with the humanized representation of this duration object ("2 days 3 minutes")
duration.humanized()

JSP:

<l:formatDuration value="${durationInMillis}"/>