Js日期格式化

Date.prototype.format = function(mask) {   
  
    var d = this;   
  
    var zeroize = function (value, length) {   
  
        if (!length) length = 2;   
  
        value = String(value);   
  
        for (var i = 0, zeros = ''; i < (length - value.length); i++) {   
  
            zeros += '0';   
  
        }   
  
        return zeros + value;   
  
    };     
  
    return mask.replace(/"[^"]*"|'[^']*'|\b(?:d{1,4}|m{1,4}|yy(?:yy)?|([hHMstT])\1?|[lLZ])\b/g, function($0) {   
  
        switch($0) {   
  
            case 'd':   return d.getDate();   
  
            case 'dd':  return zeroize(d.getDate());   
  
            case 'ddd': return ['Sun','Mon','Tue','Wed','Thr','Fri','Sat'][d.getDay()];   
  
            case 'dddd':    return ['Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday'][d.getDay()];   
  
            case 'M':   return d.getMonth() + 1;   
  
            case 'MM':  return zeroize(d.getMonth() + 1);   
  
            case 'MMM': return ['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec'][d.getMonth()];   
  
            case 'MMMM':    return ['January','February','March','April','May','June','July','August','September','October','November','December'][d.getMonth()];   
  
            case 'yy':  return String(d.getFullYear()).substr(2);   
  
            case 'yyyy':    return d.getFullYear();   
  
            case 'h':   return d.getHours() % 12 || 12;   
  
            case 'hh':  return zeroize(d.getHours() % 12 || 12);   
  
            case 'H':   return d.getHours();   
  
            case 'HH':  return zeroize(d.getHours());   
  
            case 'm':   return d.getMinutes();   
  
            case 'mm':  return zeroize(d.getMinutes());   
  
            case 's':   return d.getSeconds();   
  
            case 'ss':  return zeroize(d.getSeconds());   
  
            case 'l':   return zeroize(d.getMilliseconds(), 3);   
  
            case 'L':   var m = d.getMilliseconds();   
  
                    if (m > 99) m = Math.round(m / 10);   
  
                    return zeroize(m);   
  
            case 'tt':  return d.getHours() < 12 ? 'am' : 'pm';   
  
            case 'TT':  return d.getHours() < 12 ? 'AM' : 'PM';   
  
            case 'Z':   return d.toUTCString().match(/[A-Z]+$/);   
  
            // Return quoted strings with the surrounding quotes removed   
  
            default:    return $0.substr(1, $0.length - 2);   
  
        }   
  
    });   
  
}; 

http://www.cnblogs.com/ungshow/archive/2009/03/13/1410943.html