Javascript function to show how long ago a timestamp was as a pretty string

gistfile1.js

function timeAgo(time){
  var units = [
    { name: "second", limit: 60, in_seconds: 1 },
    { name: "minute", limit: 3600, in_seconds: 60 },
    { name: "hour", limit: 86400, in_seconds: 3600  },
    { name: "day", limit: 604800, in_seconds: 86400 },
    { name: "week", limit: 2629743, in_seconds: 604800  },
    { name: "month", limit: 31556926, in_seconds: 2629743 },
    { name: "year", limit: null, in_seconds: 31556926 }
  ];
  var diff = (new Date() - new Date(time*1000)) / 1000;
  if (diff < 5) return "now";
  
  var i = 0, unit;
  while (unit = units[i++]) {
    if (diff < unit.limit || !unit.limit){
      var diff =  Math.floor(diff / unit.in_seconds);
      return diff + " " + unit.name + (diff>1 ? "s" : "");
    }
  };
}

  /**
 * Converts a timestamp to how long ago syntax
 * @param time The time in seconds 
 * @return The formatted time
 */
public static String timeAgo(int time)
{
    Unit[] units = new Unit[]
    {
        new Unit("s", 60, 1),
        new Unit("m", 3600, 60),
        new Unit("h", 86400, 3600),
        new Unit("d", 604800, 86400),
        new Unit("w", 2629743, 604800),
        new Unit("m", 31556926, 2629743),
        new Unit("y", 0, 31556926)
    };

    long currentTime = System.currentTimeMillis();
    int difference = (int)((currentTime / 1000) - (time));

    if (currentTime < 5)
    {
        return "now";
    }

    int i = 0;
    Unit unit = null;
    while ((unit = units[i++]) != null) 
    {
        if (difference < unit.limit || unit.limit == 0)
        {
            int newDiff =  (int)Math.floor(difference / unit.inSeconds);
            return newDiff + "" + unit.name;
        }
    }

    return "";
}

static class Unit
{
    public String name;
    public int limit;
    public int inSeconds;

    public Unit(String name, int limit, int inSeconds)
    {
        this.name = name;
        this.limit = limit;
        this.inSeconds = inSeconds;
    }
}

Ported to Java: https://gist.github.com/1333916

while (unit = units[i++])

Need var here!

Here's an updated version for ES6 :)

/**
 * Returns a human-friendly "time ago" string for the given date, and switches to Locale Date String if date is older than 4 days ago.
 * Examples:
 * - a few moments ago
 * - 50 seconds ago
 * - 1 minute ago
 * - 2 hours ago
 * - 3 days ago
 * - {locale date string}
 *
 * @param timestamp {Date|string}
 * @returns {string}
 */
export function timeAgo(timestamp) {
  if (!timestamp) {
    return '';
  }
  if (typeof timestamp === 'string') {
    timestamp = new Date(timestamp);
  }
  const units = [
    {name: "second", limit: 60, in_seconds: 1},
    {name: "minute", limit: 3600, in_seconds: 60},
    {name: "hour", limit: 86400, in_seconds: 3600},
    {name: "day", limit: 345600, in_seconds: 86400}
  ];
  let diff = (new Date().getTime() - timestamp.getTime()) / 1000;
  if (diff < 5) return "a few moments ago";
  let _ago;
  for (const unit of units) {
    if (diff < unit.limit){
      diff = Math.floor(diff / unit.in_seconds);
      _ago = diff + " " + unit.name + (diff>1 ? "s" : "");
      break;
    }
  }
  if (_ago) {
    return _ago + ' ago';
  } else {
    return timestamp.toLocaleDateString();
  }
}