separating http call from ui logic and back to result

api.js

export function getvals(url){
    return fetch(url,
    {
      method: "GET",
      headers: {
        'Accept': 'application/json',
        'Content-Type': 'application/json',
      },
    })
    .then((response) => response.json())
    .then((responseData) => {
      return responseData;
    })
    .catch(error => console.warn(error));
  }

index.ios.js

import React, { Component } from 'react';
import {
  AppRegistry,
  StyleSheet,
  Text,
  View
} from 'react-native';
import {getvals} from './api';

var REQUEST_URL = 'https://raw.githubusercontent.com/facebook/react-native/master/docs/MoviesExample.json';

class Project extends Component {

  constructor(props) {
    super(props);
    this.state = {
     Total:0
    };
  }
   componentDidMount() {
    this.fetchData();
  }
  
  fetchData() {
   getvals(REQUEST_URL).then(responseData=>{
      this.setState({ Total: responseData.total})
   })
  }
  render() {
    return (
      <View style={styles.container}>
        <Text style={styles.instructions}>
        {this.state.Total} 
        </Text>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  },
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  },
  instructions: {
    textAlign: 'center',
    color: '#333333',
    marginBottom: 5,
  },
});

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