金额千分位格式化的 JS 方法

/*
* 参数说明：
* number：要格式化的数字
* decimals：保留几位小数
* dec_point：小数点符号
* thousands_sep：千分位符号
* roundtag:舍入参数，默认 "ceil" 向上取,"floor"向下取,"round" 四舍五入
**/
function formatMoney(number, decimals, dec_point, thousands_sep, roundtag) {
    if (!number) {
        number = 0;
    }
    if (!decimals) {
        decimals = 2;//默认保留2位小数
    }
    if (!dec_point) {
        dec_point = '.';
    }
    if(!thousands_sep){
        thousands_sep = ',';
    }
    if(!roundtag){
        roundtag = 'round';
    }
    number = (number + '').replace(/[^0-9+-Ee.]/g, '');
    roundtag = roundtag || "ceil"; //"ceil","floor","round"
    var n = !isFinite(+number) ? 0 : +number,
        prec = !isFinite(+decimals) ? 0 : Math.abs(decimals),
        sep = (typeof thousands_sep === 'undefined') ? ',' : thousands_sep,
        dec = (typeof dec_point === 'undefined') ? '.' : dec_point,
        s = '',
        toFixedFix = function (n, prec) {
            var k = Math.pow(10, prec);
            return '' + parseFloat(Math[roundtag](parseFloat((n * k).toFixed(prec * 2))).toFixed(prec * 2)) / k;
        };
    s = (prec ? toFixedFix(n, prec) : '' + Math.round(n)).split('.');
    var re = /(-?\d+)(\d{3})/;
    while (re.test(s[0])) {
        s[0] = s[0].replace(re, "$1" + sep + "$2");
    }

    if ((s[1] || '').length < prec) {
        s[1] = s[1] || '';
        s[1] += new Array(prec - s[1].length + 1).join('0');
    }
    return s.join(dec);
}