@buka/class-transformer-extra/dist/esm/src/number/to-big-int.js

class-transformer-extra contains methods that's aren't included in the class-transform package.

import { Transform } from 'class-transformer';
/**
 * @returns BigInt Or NaN
 */
export function ToBigInt(options) {
    return Transform(function ToBigIntTransform({ value }) {
        if (options?.optional && value === undefined)
            return undefined;
        try {
            return BigInt(value);
        }
        catch {
            return NaN;
        }
    }, options);
}