React native custom autocomplete onBlur fires before onPress

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05-10-2024

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React Native: Autocomplete onBlur Firing Before onPress - The Root of the Issue and How to Fix It

Problem: In your React Native app, you're using a custom autocomplete component, and you've noticed that the onBlur event is firing before the onPress event when selecting an item from the autocomplete suggestions list. This unexpected behavior disrupts your intended functionality, leading to confusion and potential bugs.

Understanding the Root Cause:

The core issue lies in the way React Native handles touch events and the default behavior of onBlur and onPress within your autocomplete component. When you tap on an item in the autocomplete list:

1. The onBlur event for the input field is triggered first. This occurs because the focus is lost from the input field as you tap on the suggestion list.
2. Subsequently, the onPress event for the selected item is triggered.

Scenario and Code Example:

Let's imagine you have a basic autocomplete component that renders a list of suggestions:

import React, { useState } from 'react';
import { View, TextInput, FlatList, Text } from 'react-native';

const Autocomplete = ({ suggestions, onSelect }) => {
  const [searchText, setSearchText] = useState('');
  const [selectedSuggestion, setSelectedSuggestion] = useState(null);

  const handleBlur = () => {
    console.log('onBlur triggered');
  };

  const handlePress = (item) => {
    setSelectedSuggestion(item);
    onSelect(item); // Your intended action on selecting an item
    console.log('onPress triggered', item);
  };

  return (
    <View>
      <TextInput
        value={searchText}
        onChangeText={setSearchText}
        onBlur={handleBlur}
      />
      {suggestions.length > 0 && (
        <FlatList
          data={suggestions}
          renderItem={({ item }) => (
            <Text onPress={() => handlePress(item)}>{item}</Text>
          )}
        />
      )}
    </View>
  );
};

export default Autocomplete;

In this example, onBlur is triggered before onPress when you select an item from the suggestion list, potentially causing issues if you rely on the onPress event for your desired functionality.

The Solution: Utilizing onTouchEnd

Instead of relying solely on onBlur and onPress, a more reliable approach is to use the onTouchEnd event. This event is triggered when the touch interaction is completed, ensuring that it fires after the onPress event.

Modified Code:

import React, { useState } from 'react';
import { View, TextInput, FlatList, Text, TouchableOpacity } from 'react-native';

const Autocomplete = ({ suggestions, onSelect }) => {
  // ... (rest of the code)

  const handlePress = (item) => {
    setSelectedSuggestion(item);
    onSelect(item); // Your intended action on selecting an item
    console.log('onPress triggered', item);
  };

  return (
    <View>
      {/* ... (TextInput) */}
      {suggestions.length > 0 && (
        <FlatList
          data={suggestions}
          renderItem={({ item }) => (
            <TouchableOpacity
              onTouchEnd={() => handlePress(item)} 
            >
              <Text>{item}</Text>
            </TouchableOpacity>
          )}
        />
      )}
    </View>
  );
};

export default Autocomplete;

By wrapping each suggestion item in a TouchableOpacity and using the onTouchEnd event for your handlePress function, you ensure that your selection logic is executed after the onPress event, allowing for correct functionality.

Additional Considerations:

• Event Order: The order of events can still be slightly unpredictable due to the complexities of touch handling in React Native. For critical actions, you might need to incorporate a short delay before executing code within your handlePress function.
• Custom Components: If you're using a complex autocomplete component library, review its documentation for specific event handling properties and best practices.

Conclusion:

By understanding the event order and utilizing the onTouchEnd event, you can effectively address the issue of onBlur firing before onPress in your React Native custom autocomplete component. This ensures accurate behavior and provides a more reliable approach for handling user interactions within your application.