Set value from string to number

Question

I am using React-native and the <Picker /> component.

The problem I am having, is that the value='1' is a string, but I would like it to return a number. I have seen ways to parse it, but I am unsure how to do this in react-native.

class TestPage extends Component {
  constructor(props){
    super(props);
    this.state = {
      myNumber:0
    }   
  }

  componentDidMount(){
  }

  render(){
    console.log('My value : ',this.state.myNumber);
    return (
      <View>
        <Picker
          selectedValue={this.state.myNumber}
          style={{ height: 50, width: 150 }}
          onValueChange={(itemValue) => this.setState({myNumber: itemValue})}>
          <Picker.Item label="One" value="1" />//The value here 
          <Picker.Item label="Two" value="2" />
        </Picker>
      </View>
    );
  }
}

Thank you.

Answer 1

您可以使用parseInt函数或Number构造函数将字符串解析为Number 。

this.setState({myNumber: parseInt(itemValue, 10)})

Answer 2

对我来说，更好的方法- 使用一元“ +” ：

this.setState({myNumber: +itemValue})

Answer 3

尝试使用以下内容：

onValueChange={(itemValue) => this.setState((itemValue)=>{myNumber: Number(itemValue)})}>