My HumanizeDuration.js library sounds like exactly what you want:
humanizeDuration(1); // "1 millisecond"
humanizeDuration(3000); // "3 seconds"
humanizeDuration(2012); // "2 seconds, 12 milliseconds"
humanizeDuration(97320000); // "1 day, 3 hours, 2 minutes"
Looks like my answer’s a bit late, but maybe it’ll help others looking at this question!