修复JS的四舍五入问题

Number.prototype.toFixed = function(d) { 

var s = this + ""; 

if (!d) 

d = 0; 

if (s.indexOf(".") == -1) 

s += "."; 

s += new Array(d + 1).join("0"); 

if (new RegExp("^(-|\\+)?(\\d+(\\.\\d{0," + (d + 1) + "})?)\\d*$").test(s)) { 

var s = "0" + RegExp.$2, pm = RegExp.$1, a = RegExp.$3.length, b = true; 

if (a == d + 2) { 

a = s.match(/\d/g); 

if (parseInt(a[a.length - 1]) > 4) { 

for (var i = a.length - 2; i >= 0; i--) { 

a[i] = parseInt(a[i]) + 1; 

if (a[i] == 10) { 

a[i] = 0; 

b = i != 1; 

} else 

break; 

} 

} 

s = a.join("").replace(new RegExp("(\\d+)(\\d{" + d + "})\\d$"), 

"$1.$2"); 

} 

if (b) 

s = s.substr(1); 

return (pm + s).replace(/\.$/, ""); 

} 

return this + ""; 

};