A tiny utility to convert milliseconds into a human readable format.

ms.js

// Constants.
var s = 1000;
var m = s * 60;
var h = m * 60;
var d = h * 24;
var y = d * 365.25;

// Specify the minimum a unit can be before
// `ms()` adds it to the output.

var minimums = {
	'second': 10,
	'millisecond': 1000
}

var units = ['year', 'day', 'hour', 'minute', 'second', 'millisecond'];

// The concept the function runs with is,
// to floor the amount the provided milliseconds
// divided by the number of milliseconds that represent
// the respective unit, then pass on to the next unit -
// the remainder.
var ms = function(ms){
	var map = [];

	if (ms >= y){
		map.push(Math.floor(ms/y))
		ms = ms% y
	} else {
		map.push(0)
	}

	if (ms >= d){
		map.push(Math.floor(ms/d))
		ms = ms%d
	} else {
		map.push(0)
	}

	if (ms >= h){
		map.push(Math.floor(ms/h))
		ms = ms%h
	} else {
		map.push(0)
	}

	if (ms >= m){
		map.push(Math.floor(ms/m))
		ms = ms%m
	} else {
		map.push(0)
	}

	if (ms >= s){
		map.push(Math.floor(ms/s))
		ms = ms%s
	} else {
		map.push(0)
	}

	map.push(ms);
	var filtered =  map.map(function(value, i){
		var key = units[i];
		// If the value is `0` or if the value is less than the minimun it's discarded.
		if (value === 0 || ({}.hasOwnProperty.call(minimums, key) && value < minimums[key])){
			return null;
		}

		// Handle pluralizations.
		if (value > 1){
			key += 's'
		}

		return value + ' ' + key
	}).filter(function(v){return v !== null});


	// Join with an and if the length of the filtered
	// elements is 2 or less.
	if (filtered.length <= 2){
		return filtered.join(' and ')
	}
	// Join with commas and an and if it's more than 2.
	var last = filtered.pop();
	return filtered.join(', ') + ' and ' + last
};

// Expositions.
ms.SECOND = s;
ms.MINUTE = m;
ms.HOUR = h;
ms.DAY = d;
ms.YEAR = y;

ms.minimums = minimums;
ms.units = units;

module.exports = ms;