把数字转换成货币格式

 1 Number.prototype.formatMoney = function (places, symbol, thousand, decimal) {
 2   places = !isNaN(places = Math.abs(places)) ? places : 2;
 3   symbol = symbol !== undefined ? symbol : "￥";
 4   thousand = thousand || ",";
 5   decimal = decimal || ".";
 6   var number = this,
 7     negative = number < 0 ? "-" : "",
 8     i = parseInt(number = Math.abs(+number || 0).toFixed(places), 10) + "",
 9     j = (j = i.length) > 3 ? j % 3 : 0;
10   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) : "");
11 };