CAcasesandberg·Jul 27, 2015
In React Context – Helpful Context Like AdBlock and OScasesandberg
react-context
JavaScript2015–2015
casesandberg / react-context
react-context
:shipit: Helpful Properties with React Context
2Distinct people
3Mentions
0Explicit recommenders
194GitHub stars
What to know before exploring
What it is
:shipit: Helpful Properties with React Context
GitHub
Where it is used
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What people are saying
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This week on Hacker News
Nov 7–Nov 14 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/14/2026, 1:49:46 PM UTC.
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Mentions over time
HN mentions by hour3 dated mentions
Observed mentions: 2015-07-27 17:09:09 UTC to 2015-07-27 18:41:06 UTC.
Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.
View mention counts and date ranges
| Period | Start (UTC) | End (exclusive, UTC) | Mentions | Submissions | Comments |
|---|---|---|---|---|---|
| Jul 27, 17:00 | 2015-07-27 17:00:00 UTC | 2015-07-27 18:00:00 UTC | 1 | 0 | 1 |
| Jul 27, 18:00 | 2015-07-27 18:00:00 UTC | 2015-07-27 19:00:00 UTC | 2 | 0 | 2 |
What Hacker News says
3 sourcesSorry to say, it's nothing React-specific. I understand that there is a React Developer Tools addon for Chrome that might be of interest [0].
As for me, I just turned on Javascript CPU profiling in Firefox Developer Tools, scrolled a bit, and checked what JS calls were causing the slowdown. Because the unminified source for the website is available on Github, you can quickly find and examine the functions' code directly [1].
[0]: https://chrome.google.com/webstore/detail/react-developer-to...
[1]: https://github.com/casesandberg/react-context/blob/gh-pages/...
In React Context – Helpful Context Like AdBlock and OSNo (edit: kinda). It looks like the site calls setState() on the root React component every time the scroll event is fired.
For those not familiar with React, setState() is a function that is used to update mutable state, and it is not a very cheap function, because it propagates the state through all child components, re-renders some virtual DOM, and potentially also causes actual DOM reflowing. Calling this in the scroll handler is what causes the noticeable delay.
edit: it seems like the lib itself does also call setState on scroll [0]. I don't think this is the source of the issue on the site itself, which has additional scroll handlers (for the magic non-scrolling sidebar), but it could cause similar performance problems, depending on how many child components are in your Context.
[0]: https://github.com/casesandberg/react-context/bl