smooth wheel zoom for leaflet.
This plugin provide smooth zoom ux like Google map.
var map = L.map('map', {
scrollWheelZoom: false, // disable original zoom function
smoothWheelZoom: true, // enable smooth zoom
smoothSensitivity: 1, // zoom speed. default is 1
zoomSnap: 0, // disable zoom snapping (for touchscreen zooming, and fitBounds(), etc.)
});