1

我有以下代码：

select.js：

export const getNavigationRoutes = state => state.navigation.routes
export const getNavigationIndex = state => state.navigation.index

export const getNavigationTab = createSelector(
  [getNavigationRoutes, getNavigationIndex],
  (routes, index) => (routes[index])
)

export const getBackNavSupported = createSelector(
  getNavigationTab, nevTab => nevTab.index !== 0
)

viewController.js：

import {connect} from 'react-redux'
import AppView from './AppView'
import { getBackNavSupported } from '../selectors

export default connect(
  state => ({
    backNavSupported: getBackNavSupported(state),
  }))
)(AppView)

我的状态从

{
  "index": 1,
  "key": "root",
  "routes": [
    {
      "key": "HomeTab",
      "title": "Home",
      "index": 0,
      "routes": [ /* .... */ ]
    },
    {
      "key": "FamilyTab",
      "title": "Family",
      "index": 0,
      "iconName": "people",
      "routes": [ /* .... */ ]
    },
  ]
}

至

{
  "index": 1,
  "key": "root",
  "routes": [
    {
      "key": "HomeTab",
      "title": "Home",
      "index": 0,
      "routes": [ /* ... */ ]
    },
    {
      "key": "FamilyTab",
      "title": "Family",
      "index": 1,
      "routes": [ /* ... */ ]
    }
  ]
}

我使用backNavSupportedin AppView，但是当我检查状态更改backNavSupported 后false的值时，我得到了 ，这对我来说很有意义......

我错过了什么？

更新

这就是我在组件中使用它的方式（可能是范围问题？）：

  componentDidMount() {
    const { backNavSupported} = this.props
    BackAndroid.addEventListener('hardwareBackPress', () => {
      if (backNavSupported ) {
        back()
        return true
      }
      return false
    })
  }
4

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