React Native: mobile number validation accept numeric value only

Use this validation.

mobilevalidate(text) {
    const reg = /^[0]?[789]\d{9}$/;
    if (reg.test(text) === false) {
      this.setState({
        mobilevalidate: false,
        telephone: text,
      });
      return false;
    } else {
      this.setState({
        mobilevalidate: true,
        telephone: text,
        message: '',
      });
      return true;
    }
  }

Try using keyboardType='phone-pad'.

You need to check if input string is number or not. Check below code:

 <TextInput
   ref='mobileNo'
   keyboardType="numeric"
   style={[styles.textInput, { width: '100%' }]}
   placeholder='Enter mobile number'
   onChangeText={(value) => 
   let num = value.replace(".", '');
     if(isNaN(num)){
         // Its not a number
     }else{
        this.handleChange('mobileNo', num)}  
     }
 />