react / react/react-native

zIndex in a List

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#18,616 30 comments 18 reactions 0 assignees View on GitHub

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Bug Component: FlatList Help Wanted :octocat: Issue: Author Provided Repro
Dominant language
C++
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Description

This is actually a reopen of my #16878 issue. I've got some thumbs up, so I think I am not the only one with this issue. This time I updated my example project to a pure rn project with the latest release (rn Branche)

Environment

info
  React Native Environment Info:
    System:
      OS: macOS High Sierra 10.13.6
      CPU: (8) x64 Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
      Memory: 94.53 MB / 16.00 GB
      Shell: 5.3 - /bin/zsh
    Binaries:
      Node: 10.12.0 - ~/.nvm/versions/node/v10.12.0/bin/node
      Yarn: 1.16.0 - ~/.nvm/versions/node/v10.12.0/bin/yarn
      npm: 6.9.0 - /usr/local/bin/npm
      Watchman: 4.9.0 - /usr/local/bin/watchman
    SDKs:
      iOS SDK:
        Platforms: iOS 12.1, macOS 10.14, tvOS 12.1, watchOS 5.1
      Android SDK:
        API Levels: 23
        Build Tools: 23.0.1
    IDEs:
      Xcode: 10.1/10B61 - /usr/bin/xcodebuild
    npmPackages:
      react: 16.8.3 => 16.8.3
      react-native: 0.59.8 => 0.59.8
    npmGlobalPackages:
      react-native-cli: 2.0.1
      react-native-git-upgrade: 0.2.7

Steps to Reproduce

  1. Make a list (FlatList or Array.map, it happens with both)
  2. The renderItem should get an onPress event
  3. The onPress event changes the style to a high zIndex and position absolute

Expected Behavior

I expect that the component with the high zIndex is over every other component.

Actual Behavior

It seems like it ignores the zIndex property. The behavior is exactly like I would not apply any zIndex. I can remove the zIndex and I get the same result.
Google Drive Link to a screenshot.

Reproducible Demo

Github Demo Project rn Branche This is just an extract out of my current rn project.
Expo Link (Not on the latest rn version)
Google Drive Video which show the issue

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the linked rn branch demo project and reproduce the issue using FlatList and Array.map, then inspect how the pressed component's position and zIndex are handled. Compare the behavior on the reported React Native setup; done means the pressed component with a high zIndex renders above the other list components.

Written by the indexing model from the issue text.

Assessment

Tech stack
react-native
Domain
mobile-dev
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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