最近由于项目的需要需要将数字format成货币格式，自己搞了半天效果不是很好，博客园有篇问题很好，再次转载记录一下
http://www.cnblogs.com/mingmingruyuedlut/archive/2013/05/19/3082177.html
Number.prototype.formatMoney = function (places, symbol, thousand, decimal) { places = !isNaN(places = Math.abs(places)) ? places : 2; symbol = symbol !== undefined ? symbol : "$"; thousand = thousand || ","; decimal = decimal || "."; var number = this, negative = number < 0 ? "-" : "", i = parseInt(number = Math.abs(+number || 0).toFixed(places), 10) + "", j = (j = i.length) > 3 ? j % 3 : 0; return symbol + negative + (j ? i.substr(0, j) + thousand : "") + i.substr(j).replace(/(\d{3})(?=\d)/g, "$1" + thousand) + (places ? decimal + Math.abs(number - i).toFixed(places).slice(2) : ""); };
var revenue = 12345678;
revenue.formatMoney(); // $12,345,678.00
revenue.formatMoney(0, "HK$ ");
// HK$ 12,345,678
// European formatting:
var price = 4999.99;
price.formatMoney(2, "€", ".", ",");
// €4.999,99
// It works for negative values, too:
(-500000).formatMoney(0, "£ ");// £ -500,000
function formatMoney(number, places, symbol, thousand, decimal) { number = number || 0; places = !isNaN(places = Math.abs(places)) ? places : 2; symbol = symbol !== undefined ? symbol : "$"; thousand = thousand || ","; decimal = decimal || "."; var negative = number < 0 ? "-" : "", i = parseInt(number = Math.abs(+number || 0).toFixed(places), 10) + "", j = (j = i.length) > 3 ? j % 3 : 0; return symbol + negative + (j ? i.substr(0, j) + thousand : "") + i.substr(j).replace(/(\d{3})(?=\d)/g, "$1" + thousand) + (places ? decimal + Math.abs(number - i).toFixed(places).slice(2) : ""); }
示例代码
formatMoney(54321); // $54,321 formatMoney(12345, 0, "£ "); // £ 12,345
formatMoney(12345, 2, "£ "); // £ 12,345.00
formatMoney(12345.232, 2, "£ "); // £ 12,345.23
原文：http://www.cnblogs.com/catalina-/p/5041235.html