'use strict'var accAdd = function(num1, num2) {num1 = Number(num1);num2 = Number(num2);var dec1, dec2, times;try { dec1 = countDecimals(num1)+1; } catch (e) { dec1 = 0; }try { dec2 = countDecimals(num2)+1; } catch (e) { dec2 = 0; }times = Math.pow(10, Math.max(dec1, dec2));// var result = (num1 * times + num2 * times) / times;var result = (accMul(num1, times) + accMul(num2, times)) / times;return getCorrectResult("add", num1, num2, result);// return result;
};var accSub = function(num1, num2) {num1 = Number(num1);num2 = Number(num2);var dec1, dec2, times;try { dec1 = countDecimals(num1)+1; } catch (e) { dec1 = 0; }try { dec2 = countDecimals(num2)+1; } catch (e) { dec2 = 0; }times = Math.pow(10, Math.max(dec1, dec2));// var result = Number(((num1 * times - num2 * times) / times);var result = Number((accMul(num1, times) - accMul(num2, times)) / times);return getCorrectResult("sub", num1, num2, result);// return result;
};var accDiv = function(num1, num2) {num1 = Number(num1);num2 = Number(num2);var t1 = 0, t2 = 0, dec1, dec2;try { t1 = countDecimals(num1); } catch (e) { }try { t2 = countDecimals(num2); } catch (e) { }dec1 = convertToInt(num1);dec2 = convertToInt(num2);var result = accMul((dec1 / dec2), Math.pow(10, t2 - t1));return getCorrectResult("div", num1, num2, result);// return result;
};var accMul = function(num1, num2) {num1 = Number(num1);num2 = Number(num2);var times = 0, s1 = num1.toString(), s2 = num2.toString();try { times += countDecimals(s1); } catch (e) { }try { times += countDecimals(s2); } catch (e) { }var result = convertToInt(s1) * convertToInt(s2) / Math.pow(10, times);return getCorrectResult("mul", num1, num2, result);// return result;
};

//计算小数位的长度var countDecimals = function(num) {var len = 0;try {num = Number(num);var str = num.toString().toUpperCase();if (str.split('E').length === 2) { // scientific notationvar isDecimal = false;if (str.split('.').length === 2) {str = str.split('.')[1];if (parseInt(str.split('E')[0]) !== 0) {isDecimal = true;}}let x = str.split('E');if (isDecimal) {len = x[0].length;}len -= parseInt(x[1]);} else if (str.split('.').length === 2) { // decimalif (parseInt(str.split('.')[1]) !== 0) {len = str.split('.')[1].length;}}} catch(e) {throw e;} finally {if (isNaN(len) || len < 0) {len = 0;}return len;}
};//将小数转成整数
var convertToInt = function(num) {num = Number(num);var newNum = num;var times = countDecimals(num);var temp_num = num.toString().toUpperCase();if (temp_num.split('E').length === 2) {newNum = Math.round(num * Math.pow(10, times));} else {newNum = Number(temp_num.replace(".", ""));}return newNum;
};//确认我们的计算结果无误，以防万一
var getCorrectResult = function(type, num1, num2, result) {var temp_result = 0;switch (type) {case "add":temp_result = num1 + num2;break;case "sub":temp_result = num1 - num2;break;case "div":temp_result = num1 / num2;break;case "mul":temp_result = num1 * num2;break;}if (Math.abs(result - temp_result) > 1) {return temp_result;}return result;
};

/*** 将数值四舍五入(保留2位小数)后格式化成金额形式** @param num 数值(Number或者String)* @return 金额格式的字符串,如'1,234,567.45'* @type String*/
function formatCurrency(num) {num = num.toString().replace(/\$|\,/g,'');if(isNaN(num))num = "0";sign = (num == (num = Math.abs(num)));num = Math.floor(num*100+0.50000000001);cents = num%100;num = Math.floor(num/100).toString();if(cents<10)cents = "0" + cents;for (var i = 0; i < Math.floor((num.length-(1+i))/3); i++)num = num.substring(0,num.length-(4*i+3))+','+num.substring(num.length-(4*i+3));return (((sign)?'':'-') + num + '.' + cents);
}

function fmoney(s, n) {/** 参数说明：* s：要格式化的数字* n：保留几位小数* */n = n > 0 && n <= 20 ? n : 2;s = parseFloat((s + "").replace(/[^\d\.-]/g, "")).toFixed(n) + "";var l = s.split(".")[0].split("").reverse(),r = s.split(".")[1];t = "";for (i = 0; i < l.length; i++) {t += l[i] + ((i + 1) % 3 == 0 && (i + 1) != l.length ? "," : "");}return t.split("").reverse().join("") + "." + r;
}
//调用
fmoney(9.7,2);//9.70
fmoney('12345.675910', 3);//12,345.676

function number_format(number, decimals, dec_point, thousands_sep,roundtag) {/** 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* */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"