parse = function (data) { data = Math.round(data*Math.pow(10,2))/Math.pow(10,2); if (data != null) { var lastone = data.toString().split('').pop(); if (lastone != '.') { data = parseFloat(data); } } return data; }; $('#result').html(parse(200)); // output 200 $('#result1').html(parse(200.1)); // output 200.1 $('#result2').html(parse(200.10)); // output 200.1 $('#result3').html(parse(200.109)); // output 200.11 <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.0.0/jquery.min.js"></script> <div id="result"></div> <div id="result1"></div> <div id="result2"></div> <div id="result3"></div>

我通常把它添加到我的个人库中，在一些建议和使用@TIMINeutron解决方案之后，并使其适用于十进制长度，这一个最适合:

function precise_round(num, decimals) {
   var t = Math.pow(10, decimals);   
   return (Math.round((num * t) + (decimals>0?1:0)*(Math.sign(num) * (10 / Math.pow(100, decimals)))) / t).toFixed(decimals);
}

将工作的例外报告。

我没有找到这个问题的准确解决方案，所以我自己创造了一个:

function inprecise_round(value, decPlaces) {
  return Math.round(value*Math.pow(10,decPlaces))/Math.pow(10,decPlaces);
}

function precise_round(value, decPlaces){
    var val = value * Math.pow(10, decPlaces);
    var fraction = (Math.round((val-parseInt(val))*10)/10);

    //this line is for consistency with .NET Decimal.Round behavior
    // -342.055 => -342.06
    if(fraction == -0.5) fraction = -0.6;

    val = Math.round(parseInt(val) + fraction) / Math.pow(10, decPlaces);
    return val;
}

例子:

function inprecise_round(value, decPlaces) { return Math.round(value * Math.pow(10, decPlaces)) / Math.pow(10, decPlaces); } function precise_round(value, decPlaces) { var val = value * Math.pow(10, decPlaces); var fraction = (Math.round((val - parseInt(val)) * 10) / 10); //this line is for consistency with .NET Decimal.Round behavior // -342.055 => -342.06 if (fraction == -0.5) fraction = -0.6; val = Math.round(parseInt(val) + fraction) / Math.pow(10, decPlaces); return val; } // This may produce different results depending on the browser environment console.log("342.055.toFixed(2) :", 342.055.toFixed(2)); // 342.06 on Chrome & IE10 console.log("inprecise_round(342.055, 2):", inprecise_round(342.055, 2)); // 342.05 console.log("precise_round(342.055, 2) :", precise_round(342.055, 2)); // 342.06 console.log("precise_round(-342.055, 2) :", precise_round(-342.055, 2)); // -342.06 console.log("inprecise_round(0.565, 2) :", inprecise_round(0.565, 2)); // 0.56 console.log("precise_round(0.565, 2) :", precise_round(0.565, 2)); // 0.57

Number(((Math.random() * 100) + 1).toFixed(2))

这将返回一个从1到100四舍五入到小数点后2位的随机数。

下面是https://stackoverflow.com/a/21323330/916734的TypeScript实现。它还使用了函数，并允许可选的数字偏移量。

export function round(rawValue: number | string, precision = 0, fractionDigitOffset = 0): number | string {
  const value = Number(rawValue);
  if (isNaN(value)) return rawValue;

  precision = Number(precision);
  if (precision % 1 !== 0) return NaN;

  let [ stringValue, exponent ] = scientificNotationToParts(value);

  let shiftExponent = exponentForPrecision(exponent, precision, Shift.Right);
  const enlargedValue = toScientificNotation(stringValue, shiftExponent);
  const roundedValue = Math.round(enlargedValue);

  [ stringValue, exponent ] = scientificNotationToParts(roundedValue);
  const precisionWithOffset = precision + fractionDigitOffset;
  shiftExponent = exponentForPrecision(exponent, precisionWithOffset, Shift.Left);

  return toScientificNotation(stringValue, shiftExponent);
}

enum Shift {
  Left = -1,
  Right = 1,
}

function scientificNotationToParts(value: number): Array<string> {
  const [ stringValue, exponent ] = value.toString().split('e');
  return [ stringValue, exponent ];
}

function exponentForPrecision(exponent: string, precision: number, shift: Shift): number {
  precision = shift * precision;
  return exponent ? (Number(exponent) + precision) : precision;
}

function toScientificNotation(value: string, exponent: number): number {
  return Number(`${value}e${exponent}`);
}

(Math.round((10.2)*100)/100).toFixed(2)

结果应该是10.20

(Math.round((.05)*100)/100).toFixed(2)

结果应该是:0.05

(Math.round((4.04)*100)/100).toFixed(2)

结果应该是:4.04

etc.