A simple example of using function descriptions on foo(bar)

functionDescription.js

/**
 * Foo takes any argument.
 * The return value is 'baz' in all cases.
 * @param {*} bar - Any argument
 * @param {string} [optionalArg] - An optional argument that is a string
 */
function foo(bar, optionalArg) {
  return 'baz';
}