timediff/timediff.js

Calculate a time difference in several time units.

(function () {

  var isNode = (typeof module !== 'undefined' && module && module.exports);
  var globalScope = (
      typeof global !== 'undefined'
      && (typeof window === 'undefined' || window === global.window))
    ? global : this;

  var moment;
  if (isNode) {
    moment = require('moment');
  } else {
    moment = globalScope.moment;
  }

  if (typeof moment !== 'function') {
    throw new Error('timediff requires moment.js');
    return;
  }

  function timediff (start, end, options) {
    var now = new Date();
    if (start === 'now') {
      start = now;
    }
    if (end === 'now') {
      end = now;
    }
    start = moment(start);
    if (!start.isValid()) throw 'invalid start date ' + start;
    end = moment(end);
    if (!end.isValid()) throw 'invalid end date ' + end;

    if (options instanceof String || typeof options === 'string') {
      options = {units: options};
    }

    if (typeof options === 'function') {
      options = {callback: options};
    }

    var config = {
      units: {
        years: true,
        months: true,
        weeks: true,
        days: true,
        hours: true,
        minutes: true,
        seconds: true,
        milliseconds: true
      },
      returnZeros: true,
      callback: null
    };

    if (options instanceof Object) {
      if (options.units instanceof String || typeof options.units === 'string') {
        if (options.units.search('Y') === -1) config.units.years = false;
        if (options.units.search('M') === -1) config.units.months = false;
        if (options.units.search('W') === -1) config.units.weeks = false;
        if (options.units.search('D') === -1) config.units.days = false;
        if (options.units.search('H') === -1) config.units.hours = false;
        if (options.units.search('m') === -1) config.units.minutes = false;
        if (options.units.search('S') === -1) config.units.seconds = false;
        if (options.units.search('s') === -1) config.units.milliseconds = false;
      } else if (typeof options.units == 'object') {
        if (!options.units.years  ) config.units.years   = false;
        if (!options.units.months ) config.units.months  = false;
        if (!options.units.weeks  ) config.units.weeks   = false;
        if (!options.units.days   ) config.units.days    = false;
        if (!options.units.hours  ) config.units.hours   = false;
        if (!options.units.minutes) config.units.minutes = false;
        if (!options.units.seconds) config.units.seconds = false;
        if (!options.units.milliseconds ) config.units.milliseconds  = false;
      }

      if (options.returnZeros === false) config.returnZeros = false;
      if (typeof options.callback === 'function') config.callback = options.callback;
    }

    var result = {};

    for (var unit in config.units) {
      if (config.units[unit]) {
        var value = end.diff(start, unit);
        start.add(value, unit);
        if(config.returnZeros || value != 0) result[unit] = value;
      }
    }

    if (config.callback) {
      return config.callback(result);
    }

    return result;
  }

  if (isNode) {
    module.exports = timediff;
  } else {
    globalScope.timediff = timediff;
  }
})();