Function apply does not accept arguments

🔎 Search Terms

function arguments apply

🕗 Version & Regression Information

I assume this applies in every version.

⏯ Playground Link

💻 Code

function f() {}

(function () {
	f.apply(null, arguments);
}());

🙁 Actual behavior

arguments errors with Argument of type 'IArguments' is not assignable to parameter of type '[]'.(2345)

🙂 Expected behavior

No error.

Additional information about the issue

f.apply(null, arguments) is a universal idiom for decades, albeit one that's fallen out of favor in lieu of f(...arguments) - and when one needs to set the receiver, f.apply(O, arguments) is the only choice.

Somewhat related to #68307; basically, there should probably be an "arraylike" type that all of arrays and arguments and strings and nodelists can assign to.

Duplicate of #36470. The issue provides a workaround using a local declaration that supports IArguments for apply. Alternatively use a type assertion.

I can’t use a type assertion in jsdoc, so that’s not an option for me, nor do i wish to declare a global type (esp one that’s “unsafe” per that issue comment), so it doesn’t seem like i have any workaround.

You can always assert it at the call site:

function f() {}

(function () {
	f.apply(null, arguments); // error

	f.apply(null, /** @type {any} */(arguments)); // no error
}());

Thanks, altho i wouldn’t want to cast it to any - and in my particular case i have a handful of places and I’d prefer not to litter my code with casts.

🤷‍♂️ You only have those two options.

Then i guess it’s good i filed this issue :-)

I was going to suggest this could be fixed by automagically typing arguments as IArguments & Parameters<typeof CALLEE> but for some reason intersected tuples can not be spread.

function abc(a: 'a', b: 'b', c:'c'){
    var x = arguments as Parameters<typeof abc> & IArguments;

    // WORKS: Accepts (tuple & IArguments) because it is 
    // assignable to an array
    abc.apply(null,x); 

    // ERROR: Can spread tuple but not (tuple & IArguments)
    abc(...x); 
    // A spread argument must either have a tuple 
    // type or be passed to a rest parameter. (2556)
}

You can also turn off strictBindCallApply 🫠. The "right" fix would be for b/c/a to take ArrayLike<T> versions of their argument tuples, but we don't have any type like that right now and it would be a very expensive fix that would really only pay off in this exact scenario.

hmm, i wasn't aware of that setting, but i usually am loath to disable any of the strict settings.

Would it be possible to augment the type of these methods to take | IArguments as a "cheap" fix, without needing to disable that option?

Unfortunately this exact scenario is absurdly common in any code that's not transpiled and needs to support pre-ES6 envs :-/

Adding | IArguments is basically the same as turning off strictBindCallApply, since every array is an IArguments

ah ok, gotcha.

It definitely would be amazing to have the proper ArrayLike<T> fix - for a lot of the builtin APIs - but this can sit open pending that, and I'll use the workaround of turning off strictBindCallApply.

I can’t use a type assertion in jsdoc

Just as a heads up, you can. They are parenthesized expressions with an /** @type {...} */ comment preceding them.

function f() {}

(function () {
    f.apply(null, /** @type {any} */ (arguments));
}());

Playground Link

Daniel Rosenwasser (@DanielRosenwasser)

Daniel Rosenwasser (@DanielRosenwasser) ah right thanks, i'd figured that out since then (i had to disable the no-extra-parens eslint rule). i can't use a non-null assertion, still, tho :-/

altho casting it to "any" doesn't feel like an option to me :-) what i'd want is to cast it to unknown[] or Parameters<f> or something

Fix dwarf extension build

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Function apply does not accept `arguments` #57164

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Function apply does not accept arguments #57164

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🔎 Search Terms

🕗 Version & Regression Information

⏯ Playground Link

💻 Code

🙁 Actual behavior

🙂 Expected behavior

Additional information about the issue

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MartinJohns commented on Jan 25, 2024

ljharb commented on Jan 25, 2024

Andarist commented on Jan 25, 2024

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RyanCavanaugh commented on Jan 29, 2024

ljharb commented on Jan 29, 2024

RyanCavanaugh commented on Jan 29, 2024

ljharb commented on Jan 29, 2024

DanielRosenwasser commented on Jan 29, 2024

ljharb commented on Jan 29, 2024

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Function apply does not accept `arguments` #57164