feat(eslint-plugin): [prefer-at] create rule #6411

sviat9440 · 2023-02-02T09:29:21Z

PR Checklist

Addresses an existing open issue: Rule proposal: [prefer-at] Rule to prefer array.at(-1) over array[array.length - 1] #6401
That issue was marked as accepting prs
Steps in Contributing were taken

Progress

Add type checks for Array, String, Uint8Array ...
Add ignoreFunctions option (default to false)
Add support for -2, -3 ... -i
Clear tests
Add tests for this reference
Add tests for functions
Add more examples for documentation
Fix coverage
Add tests for custom String, Array ...

typescript-eslint · 2023-02-02T09:29:23Z

Thanks for the PR, @sviat9440!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

Thanks again!

🙏 Please, if you or your company is finding typescript-eslint valuable, help us sustain the project by sponsoring it transparently on https://opencollective.com/typescript-eslint.

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packages/eslint-plugin/src/rules/prefer-at.ts

…ny number or variable

…ate statements, clear tests

codecov · 2023-03-01T11:19:04Z

Codecov Report

Merging #6411 (d0d0141) into main (997783f) will increase coverage by 0.04%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6411      +/-   ##
==========================================
+ Coverage   87.43%   87.47%   +0.04%     
==========================================
  Files         386      387       +1     
  Lines       13194    13240      +46     
  Branches     3872     3882      +10     
==========================================
+ Hits        11536    11582      +46     
  Misses       1292     1292              
  Partials      366      366

Flag	Coverage Δ
unittest	`87.47% <100.00%> (+0.04%)`	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
packages/eslint-plugin/src/rules/prefer-at.ts	`100.00% <100.00%> (ø)`

…documentation

JoshuaKGoldberg

A nice start, thank you for sending it in!

I gave it a once-over but it's hard to review more thoroughly until the unit tests are more readable. Once they're good to go I can take a deeper look. 🔍

packages/eslint-plugin/src/rules/prefer-at.ts

packages/eslint-plugin/tests/rules/prefer-at.test.ts

packages/eslint-plugin/src/rules/prefer-at.ts

packages/eslint-plugin/docs/rules/prefer-at.md

packages/eslint-plugin/src/rules/prefer-at.ts

JoshuaKGoldberg · 2023-04-05T16:55:53Z

👋 Hey @sviat9440! Just checking in, is this still something you have time for? No worries if not - I just don't want to leave it hanging.

sviat9440 · 2023-04-14T13:14:58Z

Hey, I'll do it next weekend

nx-cloud · 2023-04-16T08:40:26Z

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Co-authored-by: Josh Goldberg ✨ <git@joshuakgoldberg.com>

- remove throw UnknownNodeError - add using isTypeFlagSet utility - getTypeAtLocation cannot return undefined - the verification of the .at method has been removed

- simplify tests

- getFullName now returns the source code range

sviat9440 · 2023-04-19T06:42:16Z

@JoshuaKGoldberg fixed

JoshuaKGoldberg

Thanks for the updates! There's still a thread from before - waiting on hearing back on that one before going deeper :).

JoshuaKGoldberg · 2023-04-24T03:49:01Z

packages/eslint-plugin/src/rules/prefer-at.ts

+    function isExpectedExpressionLeft(
+      node: TSESTree.BinaryExpression,
+    ): boolean {
+      if (!isExpectedObject(node.left) || getName(node.left) !== 'length') {


Bump for this unresolved thread @sviat9440 ?

JoshuaKGoldberg · 2023-04-24T03:50:32Z

packages/eslint-plugin/src/rules/prefer-at.ts

+          },
+          node,
+          fix: fixer =>
+            fixer.replaceText(node, `${objectName}.at(-${rightName})`),


[Question] Similar lint rules such as prefer-regexp-exec and prefer-string-starts-ends-with use a util called getWrappingFixer. Have you considered using it here? There are some edge cases in their tests I think we'd want for this one.

packages/eslint-plugin/src/rules/prefer-at.ts

- fix coverage - add some exotic test cases - refactor isSupportedObject method

sviat9440 · 2023-06-29T07:15:54Z

@JoshuaKGoldberg waiting for your reply

JoshuaKGoldberg · 2023-07-17T19:18:02Z

@sviat9440 still waiting for your response on https://github.com/typescript-eslint/typescript-eslint/pull/6411/files#r1174752364 and https://github.com/typescript-eslint/typescript-eslint/pull/6411/files#r1174752796

sviat9440 · 2023-07-17T19:40:32Z

@JoshuaKGoldberg Are you kidding? I asked you a question in this thread. I will close the PR if there is no response from you.

sviat9440 · 2023-07-17T19:41:40Z

JoshuaKGoldberg · 2023-07-17T19:52:58Z

Aha! I see what the issue is - you posted the comments as Pending, in a review that hasn't been posted. So I hadn't seen them yet. Love it. I was just talking with someone about how this can be easy to do.

I'll take a look soon. Thanks for posting the screenshot! If there are other comments it'd be great if you could submit the review so I can see them.

sviat9440

Oh, I have 6 pending comments... Interestingly, some comments are published immediately, and some are not. Strange. I will keep in mind in the future.

packages/eslint-plugin/src/rules/prefer-at.ts

sviat9440 · 2023-04-16T09:12:26Z

packages/eslint-plugin/src/rules/prefer-at.ts

+    function isExpectedExpressionLeft(
+      node: TSESTree.BinaryExpression,
+    ): boolean {
+      if (!isExpectedObject(node.left) || getName(node.left) !== 'length') {


Can you give me an example where this utility will help me?

sviat9440 · 2023-06-28T13:09:59Z

packages/eslint-plugin/src/rules/prefer-at.ts

+    function isExpectedExpressionLeft(
+      node: TSESTree.BinaryExpression,
+    ): boolean {
+      if (!isExpectedObject(node.left) || getName(node.left) !== 'length') {


Bump: Can you give me an example where this utility will help me??

packages/eslint-plugin/src/rules/prefer-at.ts

JoshuaKGoldberg

👍 progress!

JoshuaKGoldberg · 2023-07-18T19:00:16Z

packages/eslint-plugin/src/rules/prefer-at.ts

+          property: TSESTree.BinaryExpression & { operator: '-' };
+        },
+      ): void {
+        if (!isExpectedExpression(node.property)) {


[Naming] I'm finding hard to read the code with the naming convention of isExpected*. It's a little vague - what does 'expected' mean? Until you fully understand the code's intent that can be hard to determine it.

What do you think about renaming them to more explicitly say what they do? E.g. instead of isExpectedExpression, something like isArrayLengthBasedLookup?

JoshuaKGoldberg · 2023-07-18T19:02:05Z

packages/eslint-plugin/src/rules/prefer-at.ts

+            name: objectName,
+          },
+          node,
+          fix: fixer =>


[Bug] Just remembered, .at's signature returns T | undefined. That's a change from the original type of T from [] lookups. We generally put anything that can break the build into suggestions fixers rather than direct fix fixers. So this should be a suggestion fixer.

JoshuaKGoldberg · 2023-07-18T19:05:45Z

packages/eslint-plugin/src/rules/prefer-at.ts

+    function isExpectedExpressionLeft(
+      node: TSESTree.BinaryExpression,
+    ): boolean {
+      if (!isExpectedObject(node.left) || getName(node.left) !== 'length') {


Behaviorally, it should help catch cases like this:

str[str['length'] - 1]

const key = 'length'; str[str[key] - 1]

For code, it would eliminate the need to manually write a function getName. Which is something a lot of our rules end up wanting. So we'd really rather than write explicit "what is the string name of this property?" logic repeatedly without a real need.

https://eslint-community.github.io/eslint-utils/api/ast-utils.html#getstaticvalue

JoshuaKGoldberg · 2023-07-18T19:06:54Z

packages/eslint-plugin/src/rules/prefer-at.ts

+    function isExpectedExpressionLeft(
+      node: TSESTree.BinaryExpression,
+    ): boolean {
+      if (!isExpectedObject(node.left) || getName(node.left) !== 'length') {


(also, for anybody seeing just this thread and wondering why we're bumping at each other 😂 the comments were pending)

JoshuaKGoldberg · 2023-10-17T19:25:50Z

👋 Hey @sviat9440! Just checking in, is this still something you have time for? No worries if not - I just don't want to leave it hanging.

JoshuaKGoldberg · 2023-11-13T12:55:45Z

Closing this PR as it's been stale for a few weeks without activity. Feel free to reopen @sviat9440 if you have time - but no worries if not! If anybody wants to drive it forward, please do post your own PR - and if you use this as a start, consider adding co-author attribution at the end of your PR description. Thanks! 😊

feat(eslint-plugin) [prefer-at] Create rule typescript-eslint#6401

125a83f

sviat9440 force-pushed the feat/6401 branch from 85e3083 to 125a83f Compare February 2, 2023 09:29

sviat9440 changed the title ~~feat(eslint-plugin) [prefer-at] Create rule #6401~~ feat(eslint-plugin): [prefer-at] Create rule Feb 2, 2023

sviat9440 changed the title ~~feat(eslint-plugin): [prefer-at] Create rule~~ feat(eslint-plugin): [prefer-at] create rule Feb 2, 2023

coyotte508 reviewed Feb 2, 2023

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sviat9440 marked this pull request as draft February 2, 2023 20:59

sviat9440 and others added 5 commits February 3, 2023 00:09

Merge branch 'main' into feat/6401

acc833e

Merge branch 'main' into feat/6401

847440c

feat(eslint-plugin): [prefer-at] add type checking and supports for a…

8389c82

…ny number or variable

feat(eslint-plugin): [prefer-at] add tests for this reference, priv…

3fd0f67

…ate statements, clear tests

feat(eslint-plugin): [prefer-at] fix documentation

10c8592

Sviatoslav Zaytsev added 3 commits March 3, 2023 09:04

feat(eslint-plugin): [prefer-at] add ignoreFunctions option, improve …

1722700

…documentation

feat(eslint-plugin): [prefer-at] fixes

9a2cae2

feat(eslint-plugin): [prefer-at] fixes

ac0bbcf

sviat9440 marked this pull request as ready for review March 3, 2023 10:05

bradzacher added the enhancement: new plugin rule New rule request for eslint-plugin label Mar 13, 2023

JoshuaKGoldberg requested changes Mar 13, 2023

View reviewed changes

JoshuaKGoldberg added the awaiting response Issues waiting for a reply from the OP or another party label Mar 13, 2023

feat(eslint-plugin): [prefer-at] docs fixes

2a181be

Co-authored-by: Josh Goldberg ✨ <git@joshuakgoldberg.com>

sviat9440 force-pushed the feat/6401 branch from 1f557c6 to 2a181be Compare April 16, 2023 08:53

Sviatoslav Zaytsev added 3 commits April 16, 2023 12:15

feat(eslint-plugin): [prefer-at] pr-fixes

c56944b

- remove throw UnknownNodeError - add using isTypeFlagSet utility - getTypeAtLocation cannot return undefined - the verification of the .at method has been removed

feat(eslint-plugin): [prefer-at] pr-fixes

cc36475

- simplify tests

feat(eslint-plugin): [prefer-at] pr-fixes

a28da89

- getFullName now returns the source code range

Merge branch 'main' into feat/6401

1d55c66

bradzacher mentioned this pull request Apr 19, 2023

Rule proposal: typescript tuples should use [] and arrays .at() for accessing members #6936

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JoshuaKGoldberg requested changes Apr 24, 2023

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mikavilpas reviewed May 18, 2023

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sviat9440 and others added 2 commits June 29, 2023 06:43

Merge branch 'main' into feat/6401

8a5451d

feat(eslint-plugin): [prefer-at] pr-fixes

d0d0141

- fix coverage - add some exotic test cases - refactor isSupportedObject method

sviat9440 commented Jul 17, 2023

View reviewed changes

JoshuaKGoldberg requested changes Jul 18, 2023

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JoshuaKGoldberg added the stale PRs or Issues that are at risk of being or have been closed due to inactivity for a prolonged period label Oct 17, 2023

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feat(eslint-plugin): [prefer-at] create rule #6411

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feat(eslint-plugin): [prefer-at] create rule #6411

feat(eslint-plugin): [prefer-at] create rule #6411

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sviat9440 commented Feb 2, 2023 • edited by Josh-Cena

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