once.js

function once(fn) {
  const { name, length } = fn;
  let called = false;

  // match .name of argument
  const wrapped = {
    [name]() {
      if (!called) {
        called = true;
        fn.apply(this, arguments);
      }
    }
  }[name];

  // match .length of argument
  Object.defineProperty(wrapped, "length", {
    value: length,
    configurable: true,
  });

  return wrapped;
}