Allow _ to be an unused variable

[feross]

In React, it's common to do:

const { width, height, ...restProps } = props
return <div ...restProps>

This assigns all the properties of props except width and height to the <div>.

Currently standard warns about width and height being unused. Would be nice if we could assign these variables to _ and _2 to mark them as unused (since we can't assign them both to _ in one assignment).

const { width: _, height: _2, ...restProps } = props
return <div ...restProps>

@dcousens Didn't you say that you have a rule modification that you use for this purpose? Can you share it?

[dcousens]

#419 (comment)

"no-unused-vars": [2, { "vars": "all", "args": "all", "argsIgnorePattern": "^_$" }],

Is what I am using, but it doesn't cover this case...

edit:

"varsIgnorePattern": "^_$"

Does not work for this case either, fwiw.

[dcousens]

@feross ignoreRestSiblings already exists though

/*eslint no-unused-vars: ["error", { "ignoreRestSiblings": true }]*/
// 'type' is ignored because it has a rest property sibling.
var { type, ...coords } = data;

[feross]

@dcousens Oh, nice. Let's use ignoreRestSiblings then!

[feross]

No ecosystem impact. This will be included in the standard v10 beta.

[tdd]

ZOMG this is SO going to make my day 😄 — the inability to rest on objects has been bugging me for a while.