# SWR dependency installed but never used — 50+ components silently suffering from race conditions and duplicate requests

**URL:** <https://talk.openelis-global.org/t/swr-dependency-installed-but-never-used-50-components-silently-suffering-from-race-conditions-and-duplicate-requests/2235>\
**Category:** Integration\
**Tags:** dev\
**Created:** [March 29, 2026, 6:10pm UTC](https://talk.openelis-global.org/t/swr-dependency-installed-but-never-used-50-components-silently-suffering-from-race-conditions-and-duplicate-requests/2235 "2026-03-29T18:10:43Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![priyanshu56](https://yyz2.discourse-cdn.com/flex030/user_avatar/talk.openelis-global.org/priyanshu56/32/1148_2.png) [@priyanshu56](https://talk.openelis-global.org/u/priyanshu56)\
**Post date:** [March 29, 2026, 6:10pm UTC](https://talk.openelis-global.org/t/swr-dependency-installed-but-never-used-50-components-silently-suffering-from-race-conditions-and-duplicate-requests/2235/1 "2026-03-29T18:10:43Z")

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**Finding**

While auditing the frontend codebase, I discovered that `swr@2.0.3` is listed as a dependency in `package.json` — but a full codebase search confirms it is imported **zero times** across the entire application.

Meanwhile, data fetching is manually handled in 50+ component files using the pattern:

```auto
useEffect(() => {
  fetch(url)
    .then(res => res.json())
    .then(data => setData(data))
}, [])

```

**Why this silently hurts users right now**

But three things are happening invisibly:

1. **Race conditions** — if a user navigates away before a slow fetch resolves, the `setState` still fires on an unmounted component. No cleanup function = potential memory leak and stale state override.

2. **Duplicate network requests** — if two components on the same dashboard both need the same data, two identical requests go out. SWR would deduplicate these automatically.

3. **No background sync** — when a lab technician switches tabs and comes back, the data is stale but shows no indication. SWR’s stale-while-revalidate would silently refresh it in the background.

**The fix — replacing one component as proof of concept**

Replace the fetch pattern in `analyzerService.js` with a single custom SWR hook:

```auto
// Before — in every component that needs analyzer data
const [data, setData] = useState(null)
useEffect(() => {
  fetch('/api/analyzers').then(r => r.json()).then(setData)
}, [])

// After — one shared hook in /src/hooks/useAnalyzers.js
import useSWR from 'swr'
const fetcher = url => fetch(url).then(r => r.json())

export function useAnalyzers() {
  const { data, error, isLoading } = useSWR('/api/analyzers', fetcher)
  return { analyzers: data, error, isLoading }
}

```

Every component that needs analyzer data now calls `useAnalyzers()` — one line, zero useEffect, zero manual state, race conditions gone, caching automatic.

**Impact if fully adopted**

The same pattern scales to every data domain in the app. The dependency is already paid for and installed. This is purely an adoption gap, not a new dependency decision.

**Proposed first step**

I’d like to start by converting one high-traffic component (e.g., the analyzer dashboard) as a proof-of-concept PR, document the custom hook pattern, and open discussion on standardizing this across `src/services/`.

---

<div class="post-metadata">

**Author:** ![aggmoulik](https://yyz2.discourse-cdn.com/flex030/user_avatar/talk.openelis-global.org/aggmoulik/32/1214_2.png) [@aggmoulik](https://talk.openelis-global.org/u/aggmoulik)\
**Post date:** [March 31, 2026, 8:21am UTC](https://talk.openelis-global.org/t/swr-dependency-installed-but-never-used-50-components-silently-suffering-from-race-conditions-and-duplicate-requests/2235/2 "2026-03-31T08:21:00Z")

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Hey @priyanshu56 I have also looked into it and it should be started now as the codebase is getting bigger.

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<div class="post-metadata">

**Author:** ![priyanshu56](https://yyz2.discourse-cdn.com/flex030/user_avatar/talk.openelis-global.org/priyanshu56/32/1148_2.png) [@priyanshu56](https://talk.openelis-global.org/u/priyanshu56)\
**Post date:** [April 3, 2026, 11:23am UTC](https://talk.openelis-global.org/t/swr-dependency-installed-but-never-used-50-components-silently-suffering-from-race-conditions-and-duplicate-requests/2235/3 "2026-04-03T11:23:14Z")

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Sure, I am working on this. and if you find something really crucial in the codebase. Please let me know