React native check internet speed

SpeedTest.js

export const fetchParallel = (link,header, callback) =>{

    const POOR = 150;
    const MODERATE = 550;
    const GOOD = 2000;

    const _start = new Date().getTime();

    const speedTester = RNFetchBlob
        .config({
            fileCache   : true
        })
        .fetch('GET', SPEED_TESTER_FILE, { }); // SPEED_TESTER_FILE some file address. try to download a file size of > 700kb

    const execution = Promise.all([
        fetch(link,header),
        speedTester
    ]);

    execution.then(([req, speed]) => { 
        return Promise.all([req.json(), speed.path()]) 
     })
     .then(([req, res]) => {

        callback(req);

        const _end = new Date().getTime();

        const kbPerSecond = Math.floor(1024/((_end-_start)/1000));

        var slow = false;
        var good = false;

        if(kbPerSecond <= POOR){
            // very bad connection
            Warning('very bad connection');

            slow = true;

        }else if(kbPerSecond >= POOR && kbPerSecond <= MODERATE){
            // avg speed
            Warning('avg speed');

            slow = true;

        }else if(kbPerSecond >= MODERATE && kbPerSecond <= GOOD){
            // good connection
            Warning('good connection');

            good = true;

        }else if(kbPerSecond > GOOD){
            // excellent connection
            Warning('excellent connection');

            good = true;

        }else{
            // unknown type
            Warning('unknown type');

            slow = true;
        }
        RNFetchBlob.fs.unlink(res);

        if(slow){
            
        }
        if(good){

        }
     }).catch(error=>{
         // alert error
     });
}