script.js

const options = {
    key: 'PsLAtXpsPTZexBwUkO7Mx5I', // REPLACE WITH YOUR KEY !!!
};

windyInit(options, windyAPI => {
    // All the params are stored in windyAPI.store
    const { overlays, broadcast } = windyAPI;

    const windMetric = overlays.wind.metric;
    console.log(windMetric);
    // 'kt' .. actually selected metric for wind overlay
    // Read only value! Do not modify.

    overlays.wind.listMetrics();
    // ['kt', 'bft', 'm/s', 'km/h', 'mph'] .. available metrics

    overlays.wind.setMetric('bft');
    // Metric for wind was changed to bft

    broadcast.on('metricChanged', (overlay, newMetric) => {
        // Any changes of any metric can be observed here
        console.log(overlay, newMetric);
    });
});