https://granfondoguide.com/maps/cacheMapZoom.js

1function displayMapZoom() {
2    var plusZoomElement = document.createElement("div");
3    plusZoomElement.classList.add("zoom", "font-segoeui-b");
4    plusZoomElement.id = "zoom-plus";
5    plusZoomElement.innerText = "+";
6    document.getElementById("map").appendChild(plusZoomElement);
7    plusZoomElement.addEventListener("click", function (event) {
8        var currZoom = map.getCamera().zoom;
9        map.setCamera({
10            zoom: currZoom + 1
11        });
12    });
13    var minusZoomElement = document.createElement("div");
14    minusZoomElement.classList.add("zoom", "font-segoeui-b");
15    minusZoomElement.id = "zoom-minus";
16    minusZoomElement.innerText = "-";
17    document.getElementById("map").appendChild(minusZoomElement);
18    minusZoomElement.addEventListener("click", function (event) {
19        var currZoom = map.getCamera().zoom;
20        map.setCamera({
21            zoom: currZoom - 1
22        });
23    });
24}