Tuple data structure JS

tuple.js

const Tuple = (() => {
  const handler = {
    construct(target, args) {
      const obj = new target(...args);

      return new Proxy(obj, {
        get: function (target, prop) {
          if (typeof target._data[prop] !== 'function') {
            return target._data[prop];
          } else {
            return (...args) => {
              return target[prop]
                ? target[prop](...args)
                : target._data[prop](...args);
            };
          }
        },
        set() {
          throw new Error('Tuple is immutable');
        }
      });
    }
  };

  class Tuple {
    constructor(...values) {
      this._data = new Array(...values);
    }

    valueOf() {
      return [...this._data];
    }

    toString() {
      return `(${this._data.join()})`;
    }
  }

  return new Proxy(Tuple, handler);
})();