通过给prototype增加方法来让JavaScript中Date类型原生的支持和.NET中一样的format功能：

 

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);    }   });  };

 

使用示例：

var d = new Date();

alert(d.format("MM/dd/yyyy"));