[HOLD for payment 2024-06-13] [LOW] [Performance] Add no-spread-in-reduce to avoid recreating array in reduce method

[mountiny]

Problem

When you use the spread operator in an array reduce, it often leads to a partial object being copied over and over again in a loop.

// BAD
const reducedObject = myArray.reduce(
    (acc, key) => ({
        ...acc,
        [key]: someOtherObject[key],
    }),
    {},
);

Especially with large objects, this is very inefficient because ...acc will unnecessarily copy the full object on each iteration, rather than just adding the single key we want to add.

Solution

Prohibit this pattern with a new ESLint rule - no-spread-in-reduce. The above example would result in a lint error, and you might fix it with something more simple and efficient, like this:

GOOD
const reducedObject = myArray.reduce(
    (acc, key) => {
        acc[key] = someOtherObject[key];
        return acc;
    },
    {},
)

@kacper-mikolajczak

Upwork Automation - Do Not Edit

• Upwork Job URL: https://www.upwork.com/jobs/~011102640f041d624c
• Upwork Job ID: 1792878366584131584
• Last Price Increase: 2024-05-21
• Automatic offers:
• DylanDylann | Reviewer | 0

Issue Owner

Current Issue Owner: @garrettmknight

[melvin-bot]

Triggered auto assignment to @garrettmknight (NewFeature), see https://stackoverflowteams.com/c/expensify/questions/14418#:~:text=BugZero%20process%20steps%20for%20feature%20requests for more details. Please add this Feature request to a GH project, as outlined in the SO.

[melvin-bot]

Job added to Upwork: https://www.upwork.com/jobs/~011102640f041d624c

[melvin-bot]

Triggered auto assignment to Contributor-plus team member for initial proposal review - @DylanDylann (External)

[kacper-mikolajczak]

Hi @mountiny 👋

[melvin-bot]

📣 @DylanDylann 🎉 An offer has been automatically sent to your Upwork account for the Reviewer role 🎉 Thanks for contributing to the Expensify app!

Offer link
Upwork job

[lirbank]

Just to double check, is task to create a ESLint rule to catch spread in reducers?

[melvin-bot]

📣 @lirbank! 📣
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Please follow these steps:

1. Make sure you've read and understood the contributing guidelines.
2. Get the email address used to login to your Expensify account. If you don't already have an Expensify account, create one here. If you have multiple accounts (e.g. one for testing), please use your main account email.
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[mountiny]

@lirbank Hello! The task will be handled by @kacper-mikolajczak (no Help Wanted label on the issue)

However, the scope is to add the lint rule and fix all the places where its currently broken

[melvin-bot]

@garrettmknight, @mountiny, @kacper-mikolajczak, @DylanDylann Uh oh! This issue is overdue by 2 days. Don't forget to update your issues!

[DylanDylann]

Not overdue, we are waiting for PR to be ready for review

[melvin-bot]

Reviewing label has been removed, please complete the "BugZero Checklist".

[melvin-bot]

The solution for this issue has been 🚀 deployed to production 🚀 in version 1.4.79-11 and is now subject to a 7-day regression period 📆. Here is the list of pull requests that resolve this issue:

• Chore: Update eslint-config-expensify to 2.0.49 #42650

If no regressions arise, payment will be issued on 2024-06-13. 🎊

For reference, here are some details about the assignees on this issue:

• @kacper-mikolajczak does not require payment (Contractor)
• @DylanDylann requires payment automatic offer (Reviewer)

[melvin-bot]

BugZero Checklist: The PR adding this new feature has been merged! The following checklist (instructions) will need to be completed before the issue can be closed:

• [@DylanDylann] Please propose regression test steps to ensure the new feature will work correctly on production in further releases.
• [@garrettmknight] Link the GH issue for creating/updating the regression test once above steps have been agreed upon.

[garrettmknight]

@DylanDylann you've been paid out - no regression test for this one.