navigator.connection.addEventListener('change', logNetworkInfo);

function logNetworkInfo() {
    // Network type that browser uses
    console.log('type: ' + navigator.connection.type);
    // Effective bandwidth estimate
    console.log('downlink: ' + navigator.connection.downlink + ' Mb/s');
    // Effective round-trip time estimate
    console.log('rtt: ' + navigator.connection.rtt + ' ms');
    // Upper bound on the downlink speed of the first network hop
    console.log('downlinkMax: ' + navigator.connection.downlinkMax + ' Mb/s');
    // Effective connection type determined using a combination of recently
    // observed rtt and downlink values: ' +
    console.log('effectiveType: ' + navigator.connection.effectiveType);
    // True if the user has requested a reduced data usage mode from the user
    // agent.
    console.log('saveData: ' + navigator.connection.saveData);
    // Add whitespace for readability
    console.log('');
}

logNetworkInfo();