time_ago_in_words in JavaScript

time_ago_in_words.js

var time_ago_in_words = function(from, to) {
  to = to ? to : Date.now();

  var minutes = (to - from) / 60000;

  var data = [
    [0      , 'less than a minute ago'],
    [1      , 'a minute ago'],
    [2      , function(m) {return m.toFixed() + ' minutes ago';}],
    [45     , 'about 1 hour ago'],
    [90     , function(m) {return 'about ' + (m / 60).toFixed() + ' hours ago';}],
    [1440   , '1 day ago'],
    [2880   , function(m) {return (m / 1440).toFixed() + ' days ago';}],
    [43200  , 'about 1 month ago'],
    [86400  , function(m) {return (m / 43200).toFixed() + ' months ago';}],
    [52960  , 'about 1 year ago'],
    [1051200, function(m) {return (m / 525960).toFixed() + ' years ago';}],
    [Number.MAX_VALUE]
  ];

  function b_search(value, lower, pos, upper) {
    if  (data[pos][0] <= value && value < data[pos + 1][0])
      return data[pos];
    else if (value < data[pos][0])
      return b_search(value, lower, Math.floor((lower + pos - 1) / 2), pos - 1);
    else
      return b_search(value, pos + 1, Math.floor((pos + 1 + upper) / 2), upper);
  }

  var res = b_search(minutes, 0, Math.floor((data.length - 1) / 2), data.length - 1)[1];
  return (res instanceof Function) ? res(minutes) : res;
};

Line 16 should read [525960 , 'about 1 year ago'],, this is 60 * 24 * 365.25, minutes in a average year.