Rule Change: (Add destructuredArrayIgnorePattern option to no-unused-vars)

What rule do you want to change?

no-unused-vars

What change to do you want to make?

Generate fewer warnings

How do you think the change should be implemented?

A new option

Example code

// With the following option set within eslintrc rules
// "no-unused-vars": ["error", { "destructuredArrayIgnorePattern": "^_" }],

const array = ['a', 'b', 'c'];

const [a, _b, c] = array;

const newArray = [a, c];

// No "no-unused-vars" error on _b

What does the rule currently do for this code?

Currently _b would be seen as an unused variable.

What will the rule do after it’s changed?

The proposed rule would allow a pattern to be set to ignore certain deconstructed array variables from triggering no-unused-vars.

It would essentially work in the same way as the existing argsIgnorePattern option for no-unused-vars.

Participation

• I am willing to submit a pull request to implement this change.

Additional comments

Currently it is possible to avoid the no-unused-vars error by changing the example code to the following:

const [a, , c] = array;

However in my opinion this doesn’t read as well as either

const [a, _b, c] = array;

or

const [a, _, c] = array;

And so it would be great to have this option.

[nzakas]

Okay @snitin315 you’re up.

[nzakas]

@snitin315 lets see if @JJPell wants to first.