im working with map api. i try to hide the marker if the zoom level is below 15 and show the marker if the zoom level more than 15. here are my code :

const markerS = L.marker([0, 0], {icon: start}).addTo(mymap);
const api_url = 'json.php'
        async function getjson() {
        const response = await fetch(api_url);
        const data = await response.json();
        const start = (data[0])
        const zoom = mymap.getZoom();
        markerS.setLatLng([start.latitude, start.longtitude]);
        if(zoom > 15) {
        markerS.style.display == "block"
            } else {
        markerS.style.display = "none"
            }     
        }

but the if logic doesn't work. the console.log show "Uncaught (in promise) TypeError: Cannot set properties of undefined (setting 'display') at getjson"

how i can fix this?