/*** [number_format 参数说明：]* @param  {[type]} number        [number：要格式化的数字]* @param  {[type]} decimals      [decimals：保留几位小数]* @param  {[type]} dec_point     [dec_point：小数点符号]* @param  {[type]} thousands_sep [thousands_sep：千分位符号]* @param  {[type]} roundtag      [roundtag:舍入参数，默认 "ceil" 向上取,"floor"向下取,"round" 四舍五入]* @return {[type]}               [description]*    */
function number_format(number, decimals, dec_point, thousands_sep, roundtag) {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);console.log();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);
}
console.log(number_format(2, 2, ".", ",")) //"2.00"
console.log(number_format(3.7, 2, ".", ",")) //"3.70"
console.log(number_format(3, 0, ".", ",")) //"3"
console.log(number_format(9.0312, 2, ".", ",")) //"9.03"
console.log(number_format(9.00, 2, ".", ",")) //"9.00"
console.log(number_format(39.715001, 2, ".", ",", "floor")) //"39.71"
console.log(number_format(9.7, 2, ".", ",")) //"9.70"
console.log(number_format(39.7, 2, ".", ",")) //"39.70"
console.log(number_format(9.70001, 2, ".", ",")) //"9.71"
console.log(number_format(39.70001, 2, ".", ",")) //"39.71"
console.log(number_format(9996.03, 2, ".", ",")) //"9996.03"
console.log(number_format(1.797, 3, ".", ",", "floor")) //"1.797"