function passThru()

in src/js/modules/choropleth.js [1247:1300]
29 lines of code
6 McCabe index (conditional complexity)

        function passThru(d, i, nodes) {
            // Get the current event
            const event = d3.event || window.event;
            
            // Store the overlay data
            var overlayData = d;
            
            // Temporarily disable pointer events on this element
            var prev = this.style.pointerEvents;
            this.style.pointerEvents = 'none';
            
            // Get the element below
            var element = document.elementFromPoint(event.clientX, event.clientY);
            
            // Restore pointer events immediately to prevent mouse event issues
            this.style.pointerEvents = prev;
            
            // If we found an element and it's a map area
            if (element && element.classList.contains('mapArea')) {
                // Remove highlight from all paths
                d3.selectAll('.mapArea').classed('highlighted', false);
                // Add highlight to current path
                d3.select(element).classed('highlighted', true);
                
                // Get the data from the underlying element
                var baseData = d3.select(element).datum();
                
                // Show combined tooltip
                d3.select(".tooltip")
                    .style("visibility", "visible")
                    .select("#tooltip")
                    .html(() => {
                        // Combine data from both layers
                        let baseHtml = baseData.properties[self.database.currentKey] !== null ? 
                            mustache(self.database.mapping[self.database.currentIndex].tooltip, {...utilities, ...baseData.properties}) :
                            "No data available";
                            
                        let overlayHtml = overlayData.properties ? 
                            mustache(self.database.mapping[self.database.currentIndex].overlayTooltip, {...utilities, ...overlayData.properties}) :
                            "";
                            
                        return `${overlayHtml}<hr style="margin: 5px 0;">${baseHtml}`;
                    });

                // Update tooltip position
                updateTooltipPosition(event);
            } else {
                // If we're not over a map area, remove all highlights
                d3.selectAll('.mapArea').classed('highlighted', false);
            }
            
            // Prevent event from continuing
            event.stopPropagation();
        }