Focus style for TextInput in react-native

In React Native, how do you change the style of a textInput when it gets focus? Say I have something like

class MyInput extends Component {
    render () {
        return <TextInput style={styles.textInput} />;
    }
};

const stylesObj = {
    textInput: {
        height: 50,
        fontSize: 15,
        backgroundColor: 'yellow',
        color: 'black',
    }
};
const styles = StyleSheet.create(stylesObj);

And I want to change the background color on focus to green.

This documentation leads me to believe that the solution is something like

class MyInput extends Component {
    constructor (props) {
        super(props);
        this.state = {hasFocus: false};
    }

    render () {
        return (<TextInput
            style={this.state.hasFocus ? styles.focusedTextInput : styles.textInput}
            onFocus={this.setFocus.bind(this, true)}
            onBlur={this.setFocus.bind(this, false)}
        />);
    }

    setFocus (hasFocus) {
        this.setState({hasFocus});
    }
};

const stylesObj = {
    textInput: {
        height: 50,
        fontSize: 15,
        backgroundColor: 'yellow',
        color: 'black',
    }
};
const styles = StyleSheet.create({
    ...stylesObj,
    focusedTextInput: {
        ...stylesObj,
        backgroundColor: 'green',
    }
});

Ignoring potential mistakes in the styles structuring, would this be considered correct way to handle it? It seems very verbose to me.

Solution 1:

You can achieve this by passing in the onFocus and onBlur events to set and unset styles when focused and blurred:

  onFocus() {
    this.setState({
        backgroundColor: 'green'
    })
  },

  onBlur() {
    this.setState({
      backgroundColor: '#ededed'
    })
  },

And then, in the TextInput do this:

<TextInput 
    onBlur={ () => this.onBlur() }
    onFocus={ () => this.onFocus() }
    style={{ height:60, backgroundColor: this.state.backgroundColor, color: this.state.color }}  />

I've set up a full working project here. I hope this helps!

https://rnplay.org/apps/hYrKmQ

'use strict';

var React = require('react-native');
var {
  AppRegistry,
  StyleSheet,
  Text,
  View,
  TextInput
} = React;

var SampleApp = React.createClass({

  getInitialState() {
    return {
        backgroundColor: '#ededed',
      color: 'white'
    }
  },

  onFocus() {
        this.setState({
        backgroundColor: 'green'
    })
  },

  onBlur() {
    this.setState({
      backgroundColor: '#ededed'
    })
  },

  render: function() {
    return (
      <View style={styles.container}>
       <TextInput 
        onBlur={ () => this.onBlur() }
        onFocus={ () => this.onFocus() }
        style={{ height:60, backgroundColor: this.state.backgroundColor, color: this.state.color }}  />
      </View>
    );
  }
});

var styles = StyleSheet.create({
  container: {
    flex: 1,
    marginTop:60
  }
});

AppRegistry.registerComponent('SampleApp', () => SampleApp);

Solution 2:

Use refs, DirectManipulation and setNativeProps for more performance: https://facebook.github.io/react-native/docs/direct-manipulation.

class MyInput extends Component {
  focusedInput = () => { 
    this.textInput.setNativeProps({
      style: { backgroundColor: 'green' }
    }) 
  }

  blurredInput = () => { 
    this.textInput.setNativeProps({
      style: { backgroundColor: 'yellow' }
    }) 
  }

  render () {
      return <TextInput 
                ref={c => { this.textInput = c}} 
                style={styles.textInput}
                onFocus={this.focusedInput}
                onBlur={this.blurredInput} />
  }

}

const stylesObj = { textInput: { height: 50, fontSize: 15, backgroundColor: 'yellow', color: 'black', } }

const styles = StyleSheet.create(stylesObj)

This updates the TextInput component directly without re-rendering the component hierarchy.

Solution 3:

The best way to control the style when the element is focused / blurred is to create your own TextInput wrapper

export const MyAppTextInput = (props) => {
  return (
    <TextInput
      {...props}
    />
  );
};

Note that {...props} will pass in any property you already set or available for TextInput.

Then extend the above component by adding state to apply styles when focus / blur

export const MyAppTextInput = (props) => {
  const [isFocused, setIsFocused] = useState(false);
  return (
    <TextInput
      {...props}
      style={[props.style, isFocused && {borderWidth: 5, borderColor: 'blue'}]}
      onBlur={() => setIsFocused(false)}
      onFocus={() => setIsFocused(true)}
    />
  );
};

And remember when you use the component to bind the value like in the example (see value={passwordText}); otherwise the value will disappear on blur as a new render commences after the state change.

<MyAppTextInput
          style={styles.input}
          value={passwordText}
          textContentType="password"
          autoCompleteType="off"
          secureTextEntry
          onChangeText={text => {
            setPasswordText(text);
          }}
        />

You can of course avoid creating a wrapper but if you have more than one input it will create a mess in your input(s) parent components as you will have to add repeating logic.

Solution 4:

You can create a state to keep track of the input-state and use that state to toggle the style. Here is a simple example

const App = () => {
  const [isActive, setActive] = useState(false);

  return (
    <TextInput style={{ color: isActive ? 'black' : 'grey' }} onFocus={() => setActive(true)} onBlur={() => setActive(false)}/>
  );
}