typia/src/functional/$ParameterReader/$ParameterReader.ts

Superfast runtime validators with only one line

export const boolean = (value: string) =>
  value !== "null"
    ? value === "true" || value === "1"
      ? true
      : value === "false" || value === "0"
        ? false
        : value
    : null;

export const bigint = (value: string) =>
  value !== "null" ? toBigint(value) : null;

export const number = (value: string) =>
  value !== "null" ? toNumber(value) : null;

export const string = (value: string) => (value !== "null" ? value : null);

const toNumber = (str: string): number | string => {
  const value: number = Number(str);
  return isNaN(value) ? str : value;
};

const toBigint = (str: string): bigint | string => {
  try {
    return BigInt(str);
  } catch {
    return str;
  }
};