js浮点计算bug

function add(num1, num2) {
    const factor = Math.pow(10, Math.max(decimalPlaces(num1), decimalPlaces(num2)));
    return (Math.round(num1 * factor) + Math.round(num2 * factor)) / factor;
}

function decimalPlaces(num) {
    const match = ('' + num).match(/(?:\.(\d+))?(?:[eE]([+-]?\d+))?$/);
    if (!match) return 0;
    return Math.max(0, (match[1] ? match[1].length : 0) - (match[2] ? +match[2] : 0));
}

console.log(add(0.1, 0.2)); // 输出 0.3

const Decimal = require('decimal.js');

const result = new Decimal(0.1).plus(0.2);
console.log(result.toNumber()); // 输出 0.3

function round(num, decimals) {
    return Number(Math.round(num + 'e' + decimals) + 'e-' + decimals);
}

console.log(round(0.1 + 0.2, 10)); // 输出 0.3