OpenStreetMap

  Zoom =

Sample code

function init() {
    //initial coordinates are given: 50. Yil Parki
    let p = {lat:40.970021, lng:29.057876}
    console.log('init at', p)
    //L is global object from leaflet
    MAP = L.map('map').setView(p, 10)  //setZoom(10)
    let u = 'https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png'
    let attribution = '© OpenStreetMap contributors'
    L.tileLayer(u, {attribution}).addTo(MAP)
    let report = () => out.innerText = MAP.getZoom()
    MAP.on('zoom', report); report()
    MAP.on('click', e => console.log(e.latlng))
}

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Ref: OpenStreetMap   Leaflet JS