自从ES6以来，有一种“正确”的方法（不覆盖静态数据和创建变通方法）可以通过使用toPrecision来实现这一点

变量x=1.49999999999；console.log（x.toPrecision（4））；console.log（x.toPrecision（3））；console.log（x.toPrecision（2））；var y=数学PI；console.log（y.toPrecision（6））；console.log（y.toPrecision（5））；console.log（y.toPrecision（4））；变量z=222.987654console.log（z.toPrecision（6））；console.log（z-toPrecision（5））；console.log（z-toPrecision（4））；

然后你可以解析Float，零将“消失”。

console.log（parseFloat（（1.4999）.toPrecision（3）））；console.log（parseFloat（（1.005）.toPrecision（3）））；console.log（parseFloat（（1.0051）.toPrecision（3）））；

但它并不能解决“1.005舍入问题”，因为它是浮点分数处理过程中的固有问题。

控制台日志（1.005-0.005）；

如果您对库开放，可以使用bignumber.js

控制台日志（1.005-0.005）；console.log（新BigNumber（1.005）.减（0.005））；console.log（新BigNumber（1.005）.round（4））；console.log（新BigNumber（1.005）.round（3））；console.log（新BigNumber（1.005）.round（2））；console.log（新BigNumber（1.005）.rround（1））；<script src=“https://cdnjs.cloudflare.com/ajax/libs/bignumber.js/2.3.0/bignumber.min.js“></script>

这里有一个简单的方法：

Math.round(value * 100) / 100

不过，您可能需要继续创建一个单独的函数来为您执行此操作：

function roundToTwo(value) {
    return(Math.round(value * 100) / 100);
}

然后，只需传入值。

通过添加第二个参数，可以将其增强为任意小数位数。

function myRound(value, places) {
    var multiplier = Math.pow(10, places);

    return (Math.round(value * multiplier) / multiplier);
}

舍入问题可以通过使用指数表示法来避免。

public roundFinancial(amount: number, decimals: number) {
    return Number(Math.round(Number(`${amount}e${decimals}`)) + `e-${decimals}`);
}

2022，原生，无库，现代浏览器，清晰可读。

函数循环(价值最小分数位数，最大分数位数) {const formattedValue=value.toLocaleString（'en'{useGrouping：false，最小分数位数，最大分数位数})返回编号（格式化值）}console.log（圆形（21.891，2，3））//21.891console.log（round（1.8，2））//1.8，如果需要1.80，请删除“Number”函数。直接返回“formattedValue”。console.log（圆形（21.0001，0，1））//21console.log（圆形（0.875，3））//0.875

我的解决方案将输入视为字符串，并使用n位数字的“数学舍入”算法：取n位数字，如果数字n+1等于或大于5，则加1。它还允许指定负数，例如，将123.45舍入为-1的数字为120。它也适用于科学符号（例如1.2e-3）。我没有测量它的速度，我认为这不是最好的表现。

function safeRound( numInput, numPrecision ) {
    const strNumber = numInput.toString().replace( 'E', 'e' );
    const bSign = '+-'.indexOf( strNumber[ 0 ] ) !== -1;
    const strSign = bSign  ?  strNumber[ 0 ]  :  '';
    const numSign = strSign !== '-'  ?  +1  :  -1;
    const ixExponent = ( ixFound => ixFound !== -1  ?  ixFound  :  strNumber.length )( strNumber.indexOf( 'e' ) );
    const strExponent = strNumber.substr( ixExponent + 1 );
    const numExponent = ixExponent !== strNumber.length  ?  Number.parseInt( strExponent )  :  0;
    const ixDecimal = ( ixFound => ixFound !== -1  ?  ixFound  :  ixExponent )( strNumber.indexOf( '.' ) );
    const strInteger = strNumber.substring( !bSign  ?  0  :  1, ixDecimal );
    const strFraction = strNumber.substring( ixDecimal + 1, ixExponent );
    
    const numPrecisionAdjusted = numPrecision + numExponent;
    const strIntegerKeep = strInteger.substring( 0, strInteger.length + Math.min( 0, numPrecisionAdjusted ) ) + '0'.repeat( -Math.min( 0, numPrecisionAdjusted ) );
    const strFractionKeep = strFraction.substring( 0, Math.max( 0, numPrecisionAdjusted ) );
    const strRoundedDown = strSign + ( strIntegerKeep === ''  ?  '0'  :  strIntegerKeep ) + ( strFractionKeep === ''  ?  ''  :  '.' + strFractionKeep ) + ( strExponent === ''  ?  ''  :  'e' + strExponent );
    
    const chRoundUp = 0 <= numPrecisionAdjusted  ?  strFraction.substr( numPrecisionAdjusted, 1 )  :  ( '0' + strInteger ).substr( numPrecisionAdjusted, 1 );
    const bRoundUp = '5' <= chRoundUp && chRoundUp <= '9';
    const numRoundUp = bRoundUp  ?  numSign * Math.pow( 10, -numPrecision )  :  0;
    
    return Number.parseFloat( strRoundedDown ) + numRoundUp;
}

function safeRoundTest( numInput, numPrecision, strExpected ) {
    const strActual = safeRound( numInput, numPrecision ).toString();
    const bPassed = strActual === strExpected;
    console.log( 'numInput', numInput, 'numPrecision', numPrecision, 'strExpected', strExpected, 'strActual', strActual, 'bPassed', bPassed );
    return bPassed  ?  0  :  1;
}

function safeRoundTests() {
    let numFailed = 0;
    numFailed += safeRoundTest( 0, 0, '0' );
    numFailed += safeRoundTest( '0', 0, '0' );
    numFailed += safeRoundTest( '0.1', 0, '0' );
    numFailed += safeRoundTest( '+0.1', 0, '0' );
    numFailed += safeRoundTest( '-0.1', 0, '0' );
    numFailed += safeRoundTest( '0.1', 1, '0.1' );
    numFailed += safeRoundTest( '+0.1', 1, '0.1' );
    numFailed += safeRoundTest( '-0.1', 1, '-0.1' );
    numFailed += safeRoundTest( '0.9', 0, '1' );
    numFailed += safeRoundTest( '+0.9', 0, '1' );
    numFailed += safeRoundTest( '-0.9', 0, '-1' );
    numFailed += safeRoundTest( '0.9', 1, '0.9' );
    numFailed += safeRoundTest( '+0.9', 1, '0.9' );
    numFailed += safeRoundTest( '-0.9', 1, '-0.9' );
    numFailed += safeRoundTest( '0.5', 0, '1' );
    numFailed += safeRoundTest( '+0.5', 0, '1' );
    numFailed += safeRoundTest( '-0.5', 0, '-1' );
    numFailed += safeRoundTest( '0.4999', 0, '0' );
    numFailed += safeRoundTest( '+0.4999', 0, '0' );
    numFailed += safeRoundTest( '-0.4999', 0, '0' );
    numFailed += safeRoundTest( '1.005', 2, '1.01' );
    numFailed += safeRoundTest( '1.00499999999', 2, '1' );
    numFailed += safeRoundTest( '012.3456', -4, '0' );
    numFailed += safeRoundTest( '012.3456', -3, '0' );
    numFailed += safeRoundTest( '012.3456', -2, '0' );
    numFailed += safeRoundTest( '012.3456', -1, '10' );
    numFailed += safeRoundTest( '012.3456', 0, '12' );
    numFailed += safeRoundTest( '012.3456', 1, '12.3' );
    numFailed += safeRoundTest( '012.3456', 2, '12.35' );
    numFailed += safeRoundTest( '012.3456', 3, '12.346' );
    numFailed += safeRoundTest( '012.3456', 4, '12.3456' );
    numFailed += safeRoundTest( '012.3456', 5, '12.3456' );
    numFailed += safeRoundTest( '12.', 0, '12' );
    numFailed += safeRoundTest( '.12', 2, '0.12' );
    numFailed += safeRoundTest( '0e0', 0, '0' );
    numFailed += safeRoundTest( '1.2e3', 0, '1200' );
    numFailed += safeRoundTest( '1.2e+3', 0, '1200' );
    numFailed += safeRoundTest( '1.2e-3', 0, '0' );
    numFailed += safeRoundTest( '1.2e-3', 3, '0.001' );
    numFailed += safeRoundTest( '1.2e-3', 4, '0.0012' );
    numFailed += safeRoundTest( '1.2e-3', 5, '0.0012' );
    numFailed += safeRoundTest( '+12.', 0, '12' );
    numFailed += safeRoundTest( '+.12', 2, '0.12' );
    numFailed += safeRoundTest( '+0e0', 0, '0' );
    numFailed += safeRoundTest( '+1.2e3', 0, '1200' );
    numFailed += safeRoundTest( '+1.2e+3', 0, '1200' );
    numFailed += safeRoundTest( '+1.2e-3', 0, '0' );
    numFailed += safeRoundTest( '+1.2e-3', 3, '0.001' );
    numFailed += safeRoundTest( '+1.2e-3', 4, '0.0012' );
    numFailed += safeRoundTest( '+1.2e-3', 5, '0.0012' );
    numFailed += safeRoundTest( '-12.', 0, '-12' );
    numFailed += safeRoundTest( '-.12', 2, '-0.12' );
    numFailed += safeRoundTest( '-0e0', 0, '0' );
    numFailed += safeRoundTest( '-1.2e3', 0, '-1200' );
    numFailed += safeRoundTest( '-1.2e+3', 0, '-1200' );
    numFailed += safeRoundTest( '-1.2e-3', 0, '0' );
    numFailed += safeRoundTest( '-1.2e-3', 3, '-0.001' );
    numFailed += safeRoundTest( '-1.2e-3', 4, '-0.0012' );
    numFailed += safeRoundTest( '-1.2e-3', 5, '-0.0012' );
    numFailed += safeRoundTest( '9876.543e210', 0, '9.876543e+213' );
    numFailed += safeRoundTest( '9876.543e210', -210, '9.877e+213' );
    numFailed += safeRoundTest( '9876.543e210', -209, '9.8765e+213' );
    numFailed += safeRoundTest( '9876.543e+210', 0, '9.876543e+213' );
    numFailed += safeRoundTest( '9876.543e+210', -210, '9.877e+213' );
    numFailed += safeRoundTest( '9876.543e+210', -209, '9.8765e+213' );
    numFailed += safeRoundTest( '9876.543e-210', 213, '9.876543e-207' );
    numFailed += safeRoundTest( '9876.543e-210', 210, '9.877e-207' );
    numFailed += safeRoundTest( '9876.543e-210', 211, '9.8765e-207' );
    console.log( 'numFailed', numFailed );
}

safeRoundTests();

根据评论中已给出的答案，链接至http://jsfiddle.net/AsRqx/，下面的一个对我来说很好。

function C(num)
{
    return +(Math.round(num + "e+2") + "e-2");
}

function N(num, places)
{
    return +(Math.round(num + "e+" + places) + "e-" + places);
}

C(1.005);

N(1.005, 0);
N(1.005, 1); // Up to 1 decimal places
N(1.005, 2); // Up to 2 decimal places
N(1.005, 3); // Up to 3 decimal places