How to give color to polygon border in leaflet map

When you style a polygon you can have the border one color and the fill another.

function polystyle(feature) {
    return {
        fillColor: 'blue',
        weight: 2,
        opacity: 1,
        color: 'white',  //Outline color
        fillOpacity: 0.7
    };
}

L.geoJson(polyData, {style: polystyle}).addTo(map);