<script type="text/javascript"> var format = function (number, form) {     var forms = form.split('.'), number = '' + number, numbers = number.split('.')         , leftnumber = numbers[0].split('')         , exec = function (lastMatch) {             if (lastMatch == '0' || lastMatch == '#') {                 if (leftnumber.length) {                     return leftnumber.pop();                 } else if (lastMatch == '0') {                     return lastMatch;                 } else {                     return '';                 }             } else {                 return lastMatch;             }     }, string     string = forms[0].split('').reverse().join('').replace(/./g, exec).split('').reverse().join('');     string = leftnumber.join('') + string;     if (forms[1] && forms[1].length) {         leftnumber = (numbers[1] && numbers[1].length) ? numbers[1].split('').reverse() : [];         string += '.' + forms[1].replace(/./g, exec);     }     return string.replace(//.$/, ''); }; alert(format(123, '#.00'))                         //输出   123.00 alert(format(123, '0.##'))                         //输出   123 alert(format(123, '0000.00 '))                     //输出   0123.00 alert(format(123456, '###,###.00'))                //输出   123,456.00 </script>