Bug Report

🔎 Search Terms

TS2463 javascript

🕗 Version & Regression Information

• This is the behavior in every version I tried, and I reviewed the FAQ for entries about default

⏯ Playground Link

• TypeScript link
• JavaScript link

💻 Code

/**
 * @typedef Options
 * @property {string} maybeUndefined
 */

/**
 * @param {Options} [options]
 */
function test({
	maybeUndefined = "str",
}) {
	takesString(maybeUndefined);
}

/**
 * @param {string} str
 */
function takesString(str) {
	console.log(str);
}

test();

🙁 Actual behavior

No error is thrown.

🙂 Expected behavior

An error is thrown similar to what happens in the TypeScript equivalent of this code. Note that in the playground link I have checked all options that are supposed to make types more strict. Also note that when this code is run, you'll end up with a runtime error. The same is true for the TypeScript equivalent, but in that case you get an error in advance warning you that the code you wrote will cause issues.