downshift-js/downshift

Consider using passive event listeners

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#1650 opened on May 23, 2025

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help wantedneeds investigation

Description

When rendering a Downshift component in Chrome, I see this message logged in the console:

[Violation] Added non-passive event listener to a scroll-blocking 'touchstart' event. Consider marking event handler as 'passive' to make the page more responsive. See https://www.chromestatus.com/feature/5745543795965952

Chrome developer tools indicates that these listeners are not passive: https://github.com/downshift-js/downshift/blob/master/src/hooks/utils.js#L421-L425

Would it be possible to make these listeners passive without affecting functionality?

Contributor guide

Tech stack
javascriptreact
Domain
frontendperformance
Issue type
performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
basic JavaScriptReact hooksevent listeners
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
85
Research direction
Focus on the file src/hooks/utils.js around lines 421-425 where event listeners are added. Determine if making these listeners passive (by passing { passive: true } as the third argument to addEventListener) will break any existing functionality, such as preventing default behavior. The issue suggests adding passive listeners to improve scroll performance. Review the related Chrome documentation and test the change with downshift components. If passive listeners are safe, implement and verify there are no regressions.