js浮点数计算问题 + 金额大写转换

Posted 2020-08-08 Hello World!

  一 js浮点数计算问题解决方案:

  1.使用 NumberObject.toFixed(num) 方法

　toFixed() 方法可把 Number 四舍五入为指定小数位数的数字。

  2.较精度计算浮点数

   

//说明：javascript的加法结果会有误差，在两个浮点数相加的时候会比较明显。这个函数返回较为精确的加法结果。  
//调用：accAdd(arg1,arg2)  
//返回值：arg1加上arg2的精确结果      
function accAdd(arg1, arg2) {  
    var r1, r2, m;  
    try {  
        r1 = (1 * arg1).toString().split(".")[1].length;  
    }  
    catch (e) {  
        r1 = 0;  
    }  
    try {  
        r2 = (1 * arg2).toString().split(".")[1].length;  
    }  
    catch (e) {  
        r2 = 0;  
    }  
    m = Math.pow(10, Math.max(r1, r2));  
    return (arg1 * m + arg2 * m) / m;  
}      
        
//说明：javascript的减法结果会有误差，在两个浮点数相加的时候会比较明显。这个函数返回较为精确的减法结果。  
//调用：accSub(arg1,arg2)  
//返回值：arg1减上arg2的精确结果      
function accSub(arg1, arg2) {  
    return accAdd(arg1, -arg2);  
}      
       
//说明：javascript的乘法结果会有误差，在两个浮点数相乘的时候会比较明显。这个函数返回较为精确的乘法结果。  
//调用：accMul(arg1,arg2)  
//返回值：arg1乘以arg2的精确结果      
function accMul(arg1, arg2) {  
    var m = 0, s1 = (1 * arg1).toString(), s2 = (1 * arg2).toString();  
    try {  
        m += s1.split(".")[1].length;  
    }  
    catch (e) {  
    }  
    try {  
        m += s2.split(".")[1].length;  
    }  
    catch (e) {  
    }  
    var ss = Number(s1.replace(".", "")) * Number(s2.replace(".", "")) / Math.pow(10, m);  
    return Math.round(ss * 100) / 100;  
}      
       
//说明：javascript的除法结果会有误差，在两个浮点数相除的时候会比较明显。这个函数返回较为精确的除法结果。  
//调用：accDiv(arg1,arg2)  
//返回值：arg1除以arg2的精确结果      
function accDiv(arg1, arg2) {  
    var t1 = 0, t2 = 0, r1, r2;  
    try {  
        t1 = (1 * arg1).toString().split(".")[1].length;  
    }  
    catch (e) {  
    }  
    try {  
        t2 = (1 * arg2).toString().split(".")[1].length;  
    }  
    catch (e) {  
    }  
    with (Math) {  
        r1 = Number((1 * arg1).toString().replace(".", ""));  
        r2 = Number((1 * arg2).toString().replace(".", ""));  
        var ss = (r1 / r2) * pow(10, t2 - t1);  
        return Math.round(ss * 100) / 100;  
    }  
}

　　

二 金额大写转换

//金额大小写转换  
function convertCurrency(currencyDigits) {  
// Constants:  
var MAXIMUM_NUMBER = 99999999999.99;  
// Predefine the radix characters and currency symbols for output:  
var CN_ZERO = "零";  
var CN_ONE = "壹";  
var CN_TWO = "贰";  
var CN_THREE = "叁";  
var CN_FOUR = "肆";  
var CN_FIVE = "伍";  
var CN_SIX = "陆";  
var CN_SEVEN = "柒";  
var CN_EIGHT = "捌";  
var CN_NINE = "玖";  
var CN_TEN = "拾";  
var CN_HUNDRED = "佰";  
var CN_THOUSAND = "仟";  
var CN_TEN_THOUSAND = "万";  
var CN_HUNDRED_MILLION = "亿";  
var CN_SYMBOL = "人民币";  
var CN_DOLLAR = "元";  
var CN_TEN_CENT = "角";  
var CN_CENT = "分";  
var CN_INTEGER = "整";  
  
// Variables:  
var integral; // Represent integral part of digit number.   
var decimal; // Represent decimal part of digit number.  
var outputCharacters; // The output result.  
var parts;  
var digits, radices, bigRadices, decimals;  
var zeroCount;  
var i, p, d;  
var quotient, modulus;  
  
// Validate input string:  
currencyDigits = currencyDigits.toString();  
if (currencyDigits == "") {  
  alert("Empty input!");  
  return "";  
}  
if (currencyDigits.match(/[^,.\d]/) != null) {  
  alert("Invalid characters in the input string!");  
  return "";  
}  
if ((currencyDigits).match(/^((\d{1,3}(,\d{3})*(.((\d{3},)*\d{1,3}))?)|(\d+(.\d+)?))$/) == null) {  
  alert("Illegal format of digit number!");  
  return "";  
}  
  
// Normalize the format of input digits:  
currencyDigits = currencyDigits.replace(/,/g, ""); // Remove comma delimiters.  
currencyDigits = currencyDigits.replace(/^0+/, ""); // Trim zeros at the beginning.   
// Assert the number is not greater than the maximum number.  
if (Number(currencyDigits) > MAXIMUM_NUMBER) {  
  alert("Too large a number to convert!");  
  return "";  
}  
// http://www.knowsky.com/ Process the coversion from currency digits to characters:  
// Separate integral and decimal parts before processing coversion:  
parts = currencyDigits.split(".");  
if (parts.length > 1) {  
  integral = parts[0];  
  decimal = parts[1];  
  // Cut down redundant decimal digits that are after the second.  
  decimal = decimal.substr(0, 2);  
}  
else {  
  integral = parts[0];  
  decimal = "";  
}  
// Prepare the characters corresponding to the digits:  
digits = new Array(CN_ZERO, CN_ONE, CN_TWO, CN_THREE, CN_FOUR, CN_FIVE, CN_SIX, CN_SEVEN, CN_EIGHT,CN_NINE);  
radices = new Array("", CN_TEN, CN_HUNDRED, CN_THOUSAND);  
bigRadices = new Array("", CN_TEN_THOUSAND, CN_HUNDRED_MILLION);  
decimals = new Array(CN_TEN_CENT, CN_CENT);  
// Start processing:  
outputCharacters = "";  
// Process integral part if it is larger than 0:  
if (Number(integral) > 0) {  
  zeroCount = 0;  
  for (i = 0; i < integral.length; i++) {  
   p = integral.length - i - 1;  
   d = integral.substr(i, 1);  
   quotient = p / 4;  
   modulus = p % 4;  
   if (d == "0") {  
    zeroCount++;  
   }  
   else {  
    if (zeroCount > 0)  
    {  
     outputCharacters += digits[0];  
    }  
    zeroCount = 0;  
    outputCharacters += digits[Number(d)] + radices[modulus];  
   }  
   if (modulus == 0 && zeroCount < 4) {   
  
  
    outputCharacters += bigRadices[quotient];  
   }  
  }  
  outputCharacters += CN_DOLLAR;  
}  
// Process decimal part if there is:  
if (decimal != "") {  
  for (i = 0; i < decimal.length; i++) {  
   d = decimal.substr(i, 1);  
   if (d != "0") {  
    outputCharacters += digits[Number(d)] + decimals[i];  
   }  
  }  
}  
// Confirm and return the final output string:  
if (outputCharacters == "") {  
  outputCharacters = CN_ZERO + CN_DOLLAR;  
}  
if (decimal == "") {  
  outputCharacters += CN_INTEGER;  
}  
//outputCharacters = CN_SYMBOL + outputCharacters;  
outputCharacters = outputCharacters;  
return outputCharacters;  
}//   
//还原金额     
function rmoney(s){   
    return parseFloat(s.replace(/[^\d\.-]/g,""));    
}     
  
  
//金额合计的格式化s为要格式化的参数（浮点型），n为小数点后保留的位数      
function fmoney(s,n){  
    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;  
}     

 

 参考资料: http://blog.csdn.net/fairyhawk/article/details/7274990