Date对象格式化方法

/* * Date Format 1.2.3 * (c) 2007-2009 Steven Levithan * MIT license * * Includes enhancements by Scott Trenda * and Kris Kowal * * Accepts a date, a mask, or a date and a mask. * Returns a formatted version of the given date. * The date defaults to the current date/time. * The mask defaults to dateFormat.masks.default. */ var dateFormat = function () { var token = /d{1,4}|m{1,4}|yy(?:yy)?|([HhMsTt])\1?|[LloSZ]|"[^"]*"|'[^']*'/g,  timezone = /\b(?:[PMCEA][SDP]T|(?:Pacific|Mountain|Central|Eastern|Atlantic) (?:Standard|Daylight|Prevailing) Time|(?:GMT|UTC)(?:[-+]\d{4})?)\b/g,  timezoneClip = /[^-+\dA-Z]/g,  pad = function (val, len) {   val = String(val);   len = len || 2;   while (val.length < len) val = "0" + val;    return val;   };  // Regexes and supporting functions are cached through closure  return function (date, mask, utc) {   var dF = dateFormat;   // You can't provide utc if you skip other args (use the "UTC:" mask prefix)   if (arguments.length == 1 && Object.prototype.toString.call(date) == "[object String]" && !/\d/.test(date)) {    mask = date;    date = undefined;   }   // Passing date through Date applies Date.parse, if necessary   date = date ? new Date(date) : new Date;   if (isNaN(date)) throw SyntaxError("invalid date");   mask = String(dF.masks[mask] || mask || dF.masks["default"]);   // Allow setting the utc argument via the mask   if (mask.slice(0, 4) == "UTC:") {    mask = mask.slice(4);    utc = true;   }   var _ = utc ? "getUTC" : "get",    d = date[_ + "Date"](),    D = date[_ + "Day"](),    m = date[_ + "Month"](),    y = date[_ + "FullYear"](),    H = date[_ + "Hours"](),    M = date[_ + "Minutes"](),    s = date[_ + "Seconds"](),    L = date[_ + "Milliseconds"](),    o = utc ? 0 : date.getTimezoneOffset(),    flags = {     d:    d,     dd:   pad(d),     ddd:  dF.i18n.dayNames[D],     dddd: dF.i18n.dayNames[D + 7],     m:    m + 1,     mm:   pad(m + 1),     mmm:  dF.i18n.monthNames[m],     mmmm: dF.i18n.monthNames[m + 12],     yy:   String(y).slice(2),     yyyy: y,     h:    H ％ 12 || 12,     hh:   pad(H ％ 12 || 12),     H:    H,     HH:   pad(H),     M:    M,     MM:   pad(M),     s:    s,     ss:   pad(s),     l:    pad(L, 3),     L:    pad(L > 99 ? Math.round(L / 10) : L),    t:    H < 12 ? "a"  : "p",    tt:   H < 12 ? "am" : "pm",    T:    H < 12 ? "A"  : "P",    TT:   H < 12 ? "AM" : "PM",     Z:    utc ? "UTC" : (String(date).match(timezone) || [""]).pop().replace(timezoneClip, ""),     o:    (o > 0 ? "-" : "+") + pad(Math.floor(Math.abs(o) / 60) * 100 + Math.abs(o) ％ 60, 4),    S:    ["th", "st", "nd", "rd"][d ％ 10 > 3 ? 0 : (d ％ 100 - d ％ 10 != 10) * d ％ 10]   };   return mask.replace(token, function ($0) {   return $0 in flags ? flags[$0] : $0.slice(1, $0.length - 1);  }); };}(); // Some common format stringsdateFormat.masks = { "default":      "ddd mmm dd yyyy HH:MM:ss", shortDate:      "m/d/yy", mediumDate:     "mmm d, yyyy", longDate:       "mmmm d, yyyy", fullDate:       "dddd, mmmm d, yyyy", shortTime:      "h:MM TT", mediumTime:     "h:MM:ss TT", longTime:       "h:MM:ss TT Z", isoDate:        "yyyy-mm-dd", isoTime:        "HH:MM:ss", isoDateTime:    "yyyy-mm-dd'T'HH:MM:ss", isoUtcDateTime: "UTC:yyyy-mm-dd'T'HH:MM:ss'Z'"}; // Internationalization stringsdateFormat.i18n = { dayNames: [  "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat",  "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday" ], monthNames: [  "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec",  "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" ]}; // For convenience...Date.prototype.format = function (mask, utc) { return dateFormat(this, mask, utc);};

用法：

var now = new Date();
 
now.format("m/dd/yy");
// Returns, e.g., 6/09/07
 
// Can also be used as a standalone function
dateFormat(now, "dddd, mmmm dS, yyyy, h:MM:ss TT");
// Saturday, June 9th, 2007, 5:46:21 PM
 
// You can use one of several named masks
now.format("isoDateTime");
// 2007-06-09T17:46:21
 
// ...Or add your own
dateFormat.masks.hammerTime = 'HH:MM! "Can\'t touch this!"';
now.format("hammerTime");
// 17:46! Can't touch this!
 
// When using the standalone dateFormat function,
// you can also provide the date as a string
dateFormat("Jun 9 2007", "fullDate");
// Saturday, June 9, 2007
 
// Note that if you don't include the mask argument,
// dateFormat.masks.default is used
now.format();
// Sat Jun 09 2007 17:46:21
 
// And if you don't include the date argument,
// the current date and time is used
dateFormat();
// Sat Jun 09 2007 17:46:22
 
// You can also skip the date argument (as long as your mask doesn't
// contain any numbers), in which case the current date/time is used
dateFormat("longTime");
// 5:46:22 PM EST
 
// And finally, you can convert local time to UTC time. Either pass in
// true as an additional argument (no argument skipping allowed in this case):
dateFormat(now, "longTime", true);
now.format("longTime", true);
// Both lines return, e.g., 10:46:21 PM UTC
 
// ...Or add the prefix "UTC:" to your mask.
now.format("UTC:h:MM:ss TT Z");
// 10:46:21 PM UTC