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ESLint Plugin: Relax prefer-const for destructuring assignment #20737

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merged 1 commit into from Mar 12, 2020

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@aduth aduth commented Mar 9, 2020

Extracted from: #20693

This pull request seeks to update the default ESLint configuration of prefer-const to allow a let assignment if any of a destructuring assignment are reassigned. The intention with this change is to avoid scenarios where the developer must resort to cumbersome workarounds (like multiple destructuring assignments of let and const) when there is mixed reassignment of destructured variables. The potential downside of this change is that we lose "signalling" of intent to reassign when working with destructuring.

Before:

let { a, b } = obj; // Error: error 'b' is never reassigned, use 'const' instead.
a++;
console.log( a, b );

After:

let { a, b } = obj; // (no error, since at least one of the destructured props 'a' is reassigned)
a++;
console.log( a, b );

See rule configuration for more detail:

https://eslint.org/docs/rules/prefer-const#destructuring

I marked this as a "New Feature" instead of "Breaking Change". While technically the behavior is now different, it should not result in the introduction of any errors.

For a real-world example, see #20693 (specifically this assignment).

Testing Instructions:

Try incorporating a code snippet like those above somewhere in code, and observe the expected result.

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github-actions bot commented Mar 9, 2020

Size Change: 0 B

Total Size: 864 kB

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@nerrad nerrad left a comment

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I add my approval as a 👍 but I realize others might have comments as well so this is just a signal.

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@ntwb ntwb left a comment

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Also, no objections from me 👍🏼

@ItsJonQ
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ItsJonQ commented Mar 10, 2020

👍 from me as well!

@gziolo
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gziolo commented Mar 12, 2020

I’m fine with the change proposed 👍

@aduth
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aduth commented Mar 12, 2020

I haven't witnessed any objections in or following the meeting discussion this week, so will assume this is a fine adjustment to merge.

Thanks y'all. 👍

@aduth aduth merged commit 165365a into master Mar 12, 2020
@aduth aduth deleted the update/eslint-prefer-const-lax-let-destructuring branch March 12, 2020 13:24
@github-actions github-actions bot added this to the Gutenberg 7.8 milestone Mar 12, 2020
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5 participants