How can I make this code work for expiry date TextInput which includes (mm/yy) model?

Question

I want to create a checkout form which includes expiry date TextInput. It will look like a this (MM/YY). After adding first 2 digits it will automatically add / then the person can type last 2 digits for the year. I found this code on the other question. But it doesn't work. When you type inside the form nothing is typed. Here is the code. How can I make this code work as needed?

constructor() {
  super()
  this.state = {
    isReady: false
  }
}

componentDidMount() {
  this.setState({
    isReady: true
  })
}
onChange(text) {
    let newText = '';
    let numbers = '0123456789';

    for (var i = 0; i < text.length; i++) {
        if ( numbers.indexOf(text[i]) > -1 ) {
            newText = newText + text[i];
        }
    }
    this.setState({myNumber: newText})
}
formatFunction(cardExpiry = ""){
   //expiryDate will be in the format MMYY, so don't make it smart just format according to these requirements, if the input has less than 2 character return it otherwise append `/` character between 2nd and 3rd letter of the input.
   if(cardExpiry.length < 2){
    return cardExpiry;
   }
   else{
    return cardExpiry.substr(0, 2) + "/" + (cardExpiry.substr(2) || "")
   }
}

inputToValue(inputText){
    //if the input has more than 5 characters don't set the state
    if(inputText.length < 6){
         const tokens = inputText.split("/");
         // don't set the state if there is more than one "/" character in the given input
         if(tokens.length < 3){
            const month = Number(tokens[1]);
            const year = Number(tokens[2]);
            //don't set the state if the first two letter is not a valid month
            if(month >= 1 && month <= 12){
               let cardExpiry = month + "";
               //I used lodash for padding the month and year with  zero
               if(month > 1 || tokens.length === 2){
                    // user entered 2 for the month so pad it automatically or entered "1/" convert it to 01 automatically
                    cardExpiry = _.padStart(month, 2, "0");
               }
               //disregard changes for invalid years
               if(year > 1 && year <= 99){
                   cardExpiry += year;
               }
               this.setState({cardExpiry});
            }
         }
    }
}

render (){
   let {cardExpiry} = this.state;
  return (
    <Image style={styles.image} source={require('../img/cover.jpg')}
  >


         <Content style={styles.content}>

            <Form>
              <Item >
                <Icon active name='card'/>
                <Input keyboardType='numeric' maxLength={16} placeholder='Card Number'
                onChangeText = {(text)=> this.onChange(text)}
      value = {this.state.myNumber}/>
      </Item>

      <Grid>
      <Row>
      <Col>

              <Item style={{ marginBottom:10}}>
                <Icon active name='calendar' />
                <Input keyboardType='numeric' placeholder='MM/YY' 
                value = {this.formatFunction(cardExpiry)}
       onChangeText={this.inputToValue.bind(this)}/>
              </Item>
              </Col>
              <Col>

                      <Item style={{ marginBottom:10}}>
                        <Icon active name='lock' />
                        <Input maxLength={3} secureTextEntry={true}  placeholder='CVV'/>
                      </Item>
                      </Col>
              </Row>
              </Grid>

Answer 1

Use this code to handle your problem:

  constructor(props) {
    super(props);
    this.state = { text: '' };
  }

  handleChange = (text) => {
    let textTemp = text;
    if (textTemp[0] !== '1' && textTemp[0] !== '0') {
      textTemp = '';
    }
    if (textTemp.length === 2) {
      if (parseInt(textTemp.substring(0, 2)) > 12 || parseInt(textTemp.substring(0, 2)) == 0) {
        textTemp = textTemp[0];
      } else if (this.state.text.length === 2) {
        textTemp += '/';
      } else {
        textTemp = textTemp[0];
      }
    }
    this.setState({text: textTemp})
  }

  render() {
    return (
      <TextInput
        keyboardType={'numeric'}
        onChangeText={this.handleChange}
        value={this.state.text}
        maxLength={5}
      />
    );
  }