eslint-plugin-svelte: svelte/@typescript-eslint/no-unnecessary-condition possible false positive

Before You File a Bug Report Please Confirm You Have Done The Following…

I have tried restarting my IDE and the issue persists.
I have updated to the latest version of the packages.

What version of ESLint are you using?

8.39.0

What version of `eslint-plugin-svelte` are you using?

2.28.0

What did you do?

https://typescript-eslint.io/play/#ts=5.0.4&sourceType=module&code=KYDwDg9gTgLgBAG2PAFlYAzAXHAzjKASwDsBzOAHzgFdiATTE4OuAXhvseOYG4AoPgGMIxfDSgI2cNJjgB+OXADkKGDDBYA9JtABDALZgkAOmH6l-IA&eslintrc=N4KABGBEBOCuA2BTAzpAXGUEKQAIBcBPABxQGNoBLY-AWhXkoDt8B6Jge1tiacTJTIAhtEK0yHJgBNK+SpPRRE0aB2iRwYAL4gtQA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3TgwAXxCSgA

I’m showing here in eslint playground but the same thing happens in a .svelte file, with both svelte/@typescript-eslint/no-unnecessary-condition and @typescript-eslint/no-unnecessary-condition

<script>
export let href: string | undefined = undefined;

const url = href ?? 'http://example.com';
</script>

It will tell me that the href condition check is unnecessary since it will always be null or undefined. But it’s an export variable, so it might get some value from whoever is using the property, I’ve just defaulted it to undefined if someone doesn’t send it in.

What did you expect to happen?

No warning/error

What actually happened?

Warning: Unnecessary conditional, left-hand side of ??operator is alwaysnullorundefined. 3:13 - 3:17

Link to GitHub Repo with Minimal Reproducible Example

Additional comments

No response

About this issue

Original URL
State: open
Created a year ago
Comments: 17 (12 by maintainers)

Most upvoted comments

Yeah. It has already been reported this issue.

ota-meshi on May 17, 2023

I think you should write:

$: className =
    "w-full h-10 flex flex-row gap-3 justify-center items-center rounded px-4 shadow-md font-normal text-base text-white transition"
    + (
      variant === "primary"
      ? " bg-secondary-700 hover:bg-secondary-800"
      : variant === "secondary"
      ? " bg-primary-800 hover:bg-primary-900"
      : " bg-error-600"
    );

Also, I think overwriting the className of a reactive variable, contains an unintended error. (Refer: https://sveltejs.github.io/eslint-plugin-svelte/rules/no-reactive-reassign/)

ota-meshi on May 15, 2023