src/core/network.ts

import NetInfo from '@react-native-community/netinfo';

let networkState: 'Offline' | 'Wifi' | 'Cellular';

function getState() {
    return networkState;
}

const isOffline = () => networkState === 'Offline';

const isWifi = () => networkState === 'Wifi';

const isCellular = () => networkState === 'Cellular';

const mapState = (state: any) => {
    if (state.type === 'none') {
        networkState = 'Offline';
    } else if (state.type === 'wifi') {
        networkState = 'Wifi';
    } else {
        networkState = 'Cellular';
    }
};

async function setup() {
    try {
        const state = await NetInfo.fetch();
        mapState(state);
    } catch (e) {}

    NetInfo.addEventListener(state => {
        mapState(state);
    });
}

const Network = {
    setup,
    getState,
    isOffline,
    isWifi,
    isCellular,
};

export default Network;