Roll20 API script to contract and expand maps

map_size.js

 myGetCleanImagesrc = function (imgsrc) {
    var parts = imgsrc.match(/(.*\/images\/.*)(thumb|med|original|max)([^?]*)(\?[^?]+)?$/);
    if(parts) {
        return parts[1]+'thumb'+parts[3]+(parts[4]?parts[4]:`?${Math.round(Math.random()*9999999)}`);
    }
    return;
};
// When a map changes vertical location, resize
const x_threshold = 800;
on("change:graphic:top", function(obj, prev) {
    if (obj.get("name").startsWith("Map:")) {
        var left = obj.get("left");
        var prevLeft = prev["left"];
        
        // If below threshold, resize keeping top of image still
       if (left <= x_threshold && prevLeft > x_threshold) {
            // Save width and height
            obj.set("bar1_value",obj.get("width"));
            obj.set("bar2_value",obj.get("height"));
            // Resize down
            obj.set("width",240);
            obj.set("height",40);
            // Set to side 1
            if (obj.get("sides") != "") {
                var allSides = obj.get("sides").split("|");
                obj.set({
                    currentSide: 1,
                    imgsrc: myGetCleanImagesrc(decodeURIComponent(allSides[1]))
                });
            }
        }
        // If above threshold, return to original size, keeping bottom of image still
        if (left > x_threshold && prevLeft <= x_threshold) {
        
            // Restore size
            obj.set("width",obj.get("bar1_value"));
            obj.set("height",obj.get("bar2_value"));
            // Clear saved size
            obj.set("bar1_value","");
            obj.set("bar2_value","");
            // Set to side 0
            if (obj.get("sides") != "") {
                var allSides = obj.get("sides").split("|");
                obj.set({
                    currentSide: 0,
                    imgsrc: myGetCleanImagesrc(decodeURIComponent(allSides[0]))
                });
            }
        }
    }
});