No TS2554 in JavaScript files even though the argument is definitely required.

[jespertheend]

Bug Report

🔎 Search Terms

javascript TS2554

🕗 Version & Regression Information

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

⏯ Playground Link

• JavaScript
• TypeScript

💻 Code

function requiredArgument({
    foo = true,
}) {
    console.log(foo);
}

requiredArgument();

🙁 Actual behavior

No type error when calling requiredArgument()

🙂 Expected behavior

A type error saying Expected 1 arguments, but got 0. TS2554, since this is also the current behaviour in TypeScript files.
And when running the JavaScript code, you get a runtime error:

Uncaught TypeError: Cannot read properties of undefined (reading 'foo')

Related: #49869

[RyanCavanaugh]

Not really clear what to do about this. Destructuring is considered an implementation detail of the function, i.e. it's considered the same as its desugaring

function requiredArgument(obj) {
    const foo = obj.foo;
    console.log(foo);
}

and parameters in JavaScript are never considered required (since there's no syntactic clue either way).

You can mark this required with an @param tag.

/**
 * @param _
 */
function requiredArgument({
    foo,
}) {
    console.log(foo);
}

// Errors
requiredArgument();

[jespertheend]

Would it make sense to use the lack of = {} as a syntactic clue that the parameter is required?
After all parameter types are already inferred where possible. For example in the case above:

function requiredArgument({
    foo = true,
}) {
    console.log(foo);
}

the first parameter is already inferred to have the type:

{
    foo: true;
}

In fact if you hover over the function the reported signature is already being inferred to be required.

This reported signature is the same in both TypeScript and JavaScript, therefore it seems weird to me that adding JSDoc to the function causes behaviour to be different when calling it. Because the reported signature is the same regardless of the JSDoc tag.