javascript tofixed四舍五入的方法

javascript tofixed四舍五入的方法

<pre>

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 + "";

};

</pre>