New rule: no-unused-dependencies

[afahim]

Do we have a rule that checks if all the dependencies required are actually utilized within the file or not?

For instance, for a file with such contents

define([
    "underscore",
], function(
    _,
) {
    console.log("hi");
});

It would say something like 'warning: you have required underscore but aren't actually using it.'

[cvisco]

@afahim ESLint already has a no-unused-vars rule that accomplishes this.

[platinumazure]

Between no-unused-vars and requirejs/amd-callback-arity (which checks that you don't have too many or too few callback parameters compared to the number of dependencies you've required), I think your use case is probably covered. Try those out and let us know if you think there's a gap somewhere!

[afahim]

The issue is that by default, no-unused-args only checks if the last argument is being used or not. Unless someone specifically specifies that all args should be checked (instead of the default after-used option), only the last dependency is checked for and erred upon.

[afahim]

Here is a case where no-unused-vars doesn't detect any unused imports.

define["backbone", "underscore", "moment"],
function(backbone, underscore, moment) {
    console.log(moment);
}

[cvisco]

@afahim got it. I've never run into this particular case before since I tend to use the Simplified CommonJS Wrapper style. With that form, each unused dependency is flagged appropriately. The ESLint no-unused-vars rule's behavior makes good sense in every function except for AMD callbacks. 😞. So, if there is no way to achieve this particular case with existing ESLint rules, then this looks like a valid addition.

[cvisco]

I'm curious where the warning should be placed, though. On the callback argument or on the path in the dependency array? Any thoughts?