smart-round/_esm/index.js

Round big numbers with arbitrary precision

import Big from "big.js";
import { toBigJsRoundingModes } from "./roundingModes.js";
const getDecimalPlaces = (bigJsNumber) => bigJsNumber.toFixed().split(".")[1]?.length ?? 0;
const parse = function ({ input, maxDecimals, maxPrecision, minDecimals, }) {
    if (maxPrecision <= 0) {
        throw new Error("maxPrecision should be positive larger than 1");
    }
    if (minDecimals < 0) {
        throw new Error("minDecimals should be positive");
    }
    if (maxDecimals < 0) {
        throw new Error("maxDecimals should be positive");
    }
    if (minDecimals > maxDecimals) {
        throw new Error("minDecimals should not be larger than maxDecimals");
    }
    if (typeof input === "number" && (isNaN(input) || !isFinite(input))) {
        throw new Error("input should be a valid number");
    }
    try {
        const bigJsNumber = new Big(input.toString().replaceAll(",", ""));
        return bigJsNumber;
    }
    catch {
        throw new Error("input should be a valid number");
    }
};
export const smartRound = (maxPrecision, minDecimals, maxDecimals) => function (input, options) {
    const { locale = "en-US", 
    // Big Number default's, but just to make it explicit
    roundingMode = "round-half-up", shouldFormat = false, } = options ?? {};
    const bigJsNumber = parse({
        input,
        maxDecimals,
        maxPrecision,
        minDecimals,
    });
    // Calculate how much to reduce the precision
    // The array of digits is the precision
    const adjustment = Math.max(bigJsNumber.c.length - maxPrecision, 0);
    // Calculate how much to reduce the decimals
    const decimals = Math.max(getDecimalPlaces(bigJsNumber) - adjustment, minDecimals);
    const newDecimals = Math.min(decimals, maxDecimals);
    const string = bigJsNumber.toFixed(newDecimals, toBigJsRoundingModes(roundingMode));
    if (!shouldFormat) {
        return string;
    }
    // formats using the ","
    return new Intl.NumberFormat(locale, {
        maximumFractionDigits: newDecimals,
        minimumFractionDigits: newDecimals,
        useGrouping: true,
        // @ts-expect-error NumberFormat.format accept strings, typings are wrong. See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/NumberFormat/format#parameters
    }).format(string);
};
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