var result = Math.round(original*100)/100;

具体细节，以防代码不是自解释的。

编辑:…或者直接使用toFixed，就像Tim Büthe提议的那样。忘记了，谢谢你的提醒(还有点赞):)

countDecimals = value => { if (Math.floor(value) === value) return 0; let stringValue = value.toString().split(".")[1]; if (stringValue) { return value.toString().split(".")[1].length ? value.toString().split(".")[1].length : 0; } else { return 0; } }; formatNumber=(ans)=>{ let decimalPlaces = this.countDecimals(ans); ans = 1 * ans; if (decimalPlaces !== 0) { let onePlusAns = ans + 1; let decimalOnePlus = this.countDecimals(onePlusAns); if (decimalOnePlus < decimalPlaces) { ans = ans.toFixed(decimalPlaces - 1).replace(/\.?0*$/, ""); } else { let tenMulAns = ans * 10; let decimalTenMul = this.countDecimals(tenMulAns); if (decimalTenMul + 1 < decimalPlaces) { ans = ans.toFixed(decimalPlaces - 1).replace(/\.?0*$/, ""); } } } }

我只是给这个值加上1，然后数出原始值和增加的值中出现的十进制数字。如果我在比原始十进制数字少加1之后找到十进制数字，我只调用toFixed() with(原始小数- 1)。我还通过将原始值乘以10来检查，并遵循相同的逻辑，以防加1不会减少冗余小数位。 在JS中处理浮点数舍入的简单变通方法。我试过的大多数情况下都有效。

There is no way to avoid inconsistent rounding for prices with x.xx5 as actual value using either multiplication or division. If you need to calculate correct prices client-side you should keep all amounts in cents. This is due to the nature of the internal representation of numeric values in JavaScript. Notice that Excel suffers from the same problems so most people wouldn't notice the small errors caused by this phenomen. However errors may accumulate whenever you add up a lot of calculated values, there is a whole theory around this involving the order of calculations and other methods to minimize the error in the final result. To emphasize on the problems with decimal values, please note that 0.1 + 0.2 is not exactly equal to 0.3 in JavaScript, while 1 + 2 is equal to 3.

我认为这里的关键是首先正确地舍入，然后您可以将其转换为String。

function roundOf(n, p) {
    const n1 = n * Math.pow(10, p + 1);
    const n2 = Math.floor(n1 / 10);
    if (n1 >= (n2 * 10 + 5)) {
        return (n2 + 1) / Math.pow(10, p);
    }
    return n2 / Math.pow(10, p);
}

// All edge cases listed in this thread
roundOf(95.345, 2); // 95.35
roundOf(95.344, 2); // 95.34
roundOf(5.0364342423, 2); // 5.04
roundOf(0.595, 2); // 0.60
roundOf(0.335, 2); // 0.34
roundOf(0.345, 2); // 0.35
roundOf(551.175, 2); // 551.18
roundOf(0.3445434, 2); // 0.34

现在可以使用toFixed(p)安全地格式化这个值。 在你的具体案例中

roundOf(0.3445434, 2).toFixed(2); // 0.34

var result = Math.round(original*100)/100;

具体细节，以防代码不是自解释的。

编辑:…或者直接使用toFixed，就像Tim Büthe提议的那样。忘记了，谢谢你的提醒(还有点赞):)

function trimNumber(num, len) {
  const modulu_one = 1;
  const start_numbers_float=2;
  var int_part = Math.trunc(num);
  var float_part = String(num % modulu_one);
      float_part = float_part.slice(start_numbers_float, start_numbers_float+len);
  return int_part+'.'+float_part;
}