I have a page that apparently works nicely in Firefox, Chrome, Edge but not in IE11 which some of the target users require:
https://www.sva.se/Maps/kattsalmonella/map.html
I get the error "Object does not support this property or method" at line 323, I have read this post:
Getting error in IE11 for javascript array
and suspect something similar is going on but can't identify the problem.
A suggestion is to remove fill() from this code:
function getZoomData(){
    zoomTest= new Array(zoomKod.length).fill(0), zoomPos = new Array(zoomKod.length).fill(0), zoomNeg = new Array(zoomKod.length).fill(0);
    for(i in data2.features)
    {
        var dateparts = data2.features[i].properties["date"].split('-');
        var sampledate = new Date(dateparts[0], dateparts[1]-1);
        if(sampledate.getTime() >= minRange && sampledate.getTime() <= maxRange ){
            for(k in zoomKod){
                if(zoomKod[k] == data2.features[i].properties["NUTS_ID"]){
                    zoomTest[k] += data2.features[i].properties["samples"];
                    zoomPos[k] +=data2.features[i].properties["pos"];
                    zoomNeg[k] +=data2.features[i].properties["neg"];
                    break;
                }
            }
        }
    }
}