dateline.js

(function () {
  var DAY_NAMES = [
    "Sunday",
    "Monday",
    "Tuesday",
    "Wednesday",
    "Thursday",
    "Friday",
    "Saturday",
  ];

  var MONTH_NAMES = [
    "Jan.",
    "Feb.",
    "March",
    "April",
    "May",
    "June",
    "July",
    "Aug.",
    "Sept.",
    "Oct.",
    "Nov.",
    "Dec.",
  ];

  var ONE_DAY_IN_MS = 1000 * 60 * 60 * 24;

  var Dateline = function (dateObj) {
    if (dateObj == null) {
      dateObj = new Date();
    }

    dateObj.getAPTime = function (options) {
      if (options == null) {
        options = {};
      }

      var hours = dateObj.getHours();
      var minutes = dateObj.getMinutes();

      // Special cases: "midnight" and "noon"
      if (hours === 0 && minutes === 0) {
        return "midnight";
      } else if (hours === 12 && minutes === 0) {
        return "noon";
      }

      var timeOfDay = hours < 12 ? "a.m." : "p.m.";

      var hour = formatHours(hours);

      // Don't show minutes at the top of the hour by default
      if (showMinutes(minutes, options)) {
        return hour + " " + timeOfDay;
      }

      var minute = formatMinutes(minutes);

      return hour + ":" + minute + " " + timeOfDay;
    };

    dateObj.getAPDate = function (options) {
      if (options == null) {
        options = {};
      }

      var month = dateObj.getMonth();
      var date = dateObj.getDate();
      var year = dateObj.getFullYear();

      var monthName = MONTH_NAMES[month];

      if (useDayName(dateObj, options)) {
        return getDayOfWeek(dateObj);
      } else if (showYear(year, options)) {
        return monthName + " " + date;
      } else {
        return monthName + " " + date + ", " + year;
      }
    };

    return dateObj;
  };

  // Export for Node or browser
  if (
    typeof module !== "undefined" && module !== null ? module.exports : void 0
  ) {
    module.exports = Dateline;
  } else {
    this.Dateline = Dateline;
  }

  // # Time Helpers
  function formatHours(hours) {
    if (hours === 0) {
      return 12;
    } else if (hours > 12) {
      return hours - 12;
    } else {
      return hours;
    }
  }

  function formatMinutes(minutes) {
    return minutes < 10 ? "0" + minutes : minutes.toString();
  }

  function isTopOfHour(minutes) {
    return minutes === 0;
  }

  function showMinutes(minutes, options) {
    return isTopOfHour(minutes) && options.includeMinutes == null;
  }

  // # Date Helpers

  function showYear(year, options) {
    return year === new Date().getFullYear() && options.includeYear == null;
  }

  function getDayOfWeek(dateObj) {
    return DAY_NAMES[dateObj.getDay()];
  }

  function useDayName(dateObj, options) {
    return options.useDayNameForLastWeek != null && withinSevenDays(dateObj);
  }

  function withinSevenDays(dateObj) {
    var diffInDays = (dateObj - new Date()) / ONE_DAY_IN_MS;
    return -7 < diffInDays && diffInDays < 0;
  }
}).call(this);