Parameters required by default when generating modules from JavaScript files

TypeScript Version: 4.1.2x

Search Terms:
transpile javascript optional parameters

Code

export default function example (hello, optionalParam={}) {
  console.log(hello);
}

export default function example(hello: any, optionalParam?: object): void;

The first parameter is now required. While there is syntax to make parameters optional as shown above, shouldn't all javascript parameters be optional unless specified by a JSDoc?

Ideally there would be some configuration for this to allow a "optional by default".

Expected behavior:
https://www.typescriptlang.org/docs/handbook/type-checking-javascript-files.html#function-parameters-are-optional-by-default

Actual behavior:
Parameters are not optional by default.

Playground Link:

Related Issues:

首先阅读 handbook 中关于 JavaScript 函数参数的章节，并使用此处描述的 TypeScript 4.1.2x 行为重现该示例。调查如何检查 JavaScript 文件以及如何配置可选参数；当文档所述的默认可选行为或明确的配置选择能够一致地反映在报告的类型中时，即视为完成。