JS将number数值转化成为货币格式

JavaScript Money Format（用prototype对Number进行扩展）、

// Extend the default Number object with a formatMoney() method:
    // usage: someVar.formatMoney(decimalPlaces, symbol, thousandsSeparator, decimalSeparator)
    // defaults: (2, "$", ",", ".")
    Number.prototype.formatMoney = function (places, symbol, thousand, decimal) {
        places = !isNaN(places = Math.abs(places)) ? places : 2;
        symbol = symbol !== undefined ? symbol : "$";
        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) : "");
    };

如下便是一些转换实例：

// Default usage and custom precision/symbol :
    var revenue = 12345678;
    alert(revenue.formatMoney()); // $12,345,678.00
    alert(revenue.formatMoney(0, "HK$ ")); // HK$ 12,345,678


    // European formatting:
    var price = 4999.99;
    alert(price.formatMoney(2, "€", ".", ",")); // €4.999,99


    // It works for negative values, too:
    alert((-500000).formatMoney(0, "£ ")); // £ -500,000