TypeScript: Get time distance as human readable string

timeAgo.ts

// takes either a unix time number, string or a Date object and returns time string

export const timeAgo = (time: number | string | Date) => {
  switch (typeof time) {
    case "number":
      break;
    case "string":
      time = +new Date(time);
      break;
    case "object":
      if (time.constructor === Date) time = time.getTime();
      break;
    default:
      time = +new Date();
  }
  const time_formats = [
    [60, "seconds", 1], // 60
    [120, "1 minute ago", "1 minute from now"], // 60*2
    [3600, "minutes", 60], // 60*60, 60
    [7200, "1 hour ago", "1 hour from now"], // 60*60*2
    [86400, "hours", 3600], // 60*60*24, 60*60
    [172800, "yesterday", "tomorrow"], // 60*60*24*2
    [604800, "days", 86400], // 60*60*24*7, 60*60*24
    [1209600, "last week", "next week"], // 60*60*24*7*4*2
    [2419200, "weeks", 604800], // 60*60*24*7*4, 60*60*24*7
    [4838400, "last month", "next month"], // 60*60*24*7*4*2
    [29030400, "months", 2419200], // 60*60*24*7*4*12, 60*60*24*7*4
    [58060800, "last year", "next year"], // 60*60*24*7*4*12*2
    [2903040000, "years", 29030400], // 60*60*24*7*4*12*100, 60*60*24*7*4*12
    [5806080000, "last century", "next century"], // 60*60*24*7*4*12*100*2
    [58060800000, "centuries", 2903040000], // 60*60*24*7*4*12*100*20, 60*60*24*7*4*12*100
  ];
  /* @ts-ignore */
  let seconds = (+new Date() - time) / 1000,
    token = "ago",
    list_choice = 1;

  if (seconds == 0) {
    return "Just now";
  }
  if (seconds < 0) {
    seconds = Math.abs(seconds);
    token = "from now";
    list_choice = 2;
  }
  let i = 0,
    format;
  /* eslint-disable no-cond-assign */
  while ((format = time_formats[i++]))
    if (seconds < format[0]) {
      if (typeof format[2] == "string") return format[list_choice];
      else
        return Math.floor(seconds / format[2]) + " " + format[1] + " " + token;
    }
  return time;
};

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