number-as-string
Version:
Precise number scaling and formatting without JavaScript floating-point precision issues
45 lines (44 loc) • 1.86 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.scaleDown = scaleDown;
const utils_1 = require("./utils");
/**
* Formats a scaled number string to a number string with the specified number of decimal places.
*
* @param scaledValue - The scaled number string to format.
* @param decimals - The number of decimal places to include in the formatted number string.
* @returns The formatted number string.
*/
function scaleDown(scaledValue, decimals) {
if (decimals < 0) {
throw new Error("Decimals must be a non-negative integer");
}
let strValue = scaledValue.toString().toLowerCase();
if (["infinity", "-infinity", "nan"].includes(strValue)) {
throw new Error("Invalid scaledValue value");
}
if (strValue.startsWith("0x")) {
strValue = BigInt(strValue).toString();
}
else if (strValue.includes("e")) {
strValue = (0, utils_1.scientificToNumberString)(strValue);
}
let [integerPart, fractionalPart = ""] = strValue.split(".");
const sign = integerPart.startsWith("-") ? "-" : "";
integerPart = sign
? integerPart.slice(1).replace(/^0+/, "") || "0"
: integerPart.replace(/^0+/, "") || "0";
fractionalPart = fractionalPart.replace(/0+$/, "");
if (integerPart.length <= decimals) {
return `${sign}0.${integerPart.padStart(decimals, "0")}${fractionalPart}`;
}
else {
const trimmedFractionalPart = `${integerPart.slice(integerPart.length - decimals)}${fractionalPart}`.replace(/0+$/, "");
integerPart = integerPart.slice(0, integerPart.length - decimals);
if (trimmedFractionalPart.length === 0) {
return `${sign}${integerPart}`;
}
return `${sign}${integerPart}.${trimmedFractionalPart.replace(/\.$/, "")}`;
}
}
scaleDown("555555555555555555", 18);