Loading a map of Toronto's wards from a GeoJSON file and rendered using d3.js

toronto.js

// Load in GeoJSON data
d3.json("/media/js/toronto.json", function(json) {

    //Bind data and create one path per GeoJSON feature
    svg.select('#paths').selectAll("path")
       .data(json.features)
       .enter()
       .append("path")
       .attr("d", path)
       .attr("name", function(d) { 
            ward_id = d.properties.NAME.match(ward_id_re)[0]
            election_data = elections[ward_id]
            return "<strong>"+d.properties.NAME+"</strong><br/><b>2010</b>: "+election_data.winner+": "+election_data.percent+"%";
        })  
        .attr('ward', function(d) {
            return d.properties.NAME.match(ward_id_re)[0]
        })  
       .style("fill", function(d) {
            ward_id = d.properties.NAME.match(ward_id_re)[0]
            election_data = elections[ward_id]
            if (election_data.winner == 'Ford') {
                return '#A1DAE9'
            } else {
                return '#ebebeb'
            }   
       })  
       .style("stroke", "#000")
       .on("mouseout", function() {
          d3.select('body').select('.datamaps-hoverover').style("display", "none")
          d3.select(this).style('stroke-width', '1px');
       })  
       .on("mouseover", function() {
          d3.select(this).style('stroke-width', '4px');
        })  
       .on("mousemove", function(d) {
          var position = d3.mouse(this);
          var node = this;
          d3.select(this).style('stroke-width', '4px');
          d3.select('body').select('.datamaps-hoverover')
            .style("display", "block")
            .style('top', ( (position[1] + 30)) + "px")
            .html(function() {
                ward_id = node.attributes.ward.nodeValue
                if (ward_id < 10) {
                    ward_id = '0'+ward_id
                }   
                key = this_date.getMonth()+1 + '-' + this_date.getDate() + '-' + ward_id;
                ward_sentiment = wards[key]
                total = ward_sentiment.pos + ward_sentiment.neg
                neg_percent = 0
                pos_percent = 0
                if (total > 0) {
                    neg_percent = Math.round(ward_sentiment.neg/total*100)
                    pos_percent = Math.round(ward_sentiment.pos/total*100)
                }
                return node.attributes.name.nodeValue + "<br/><b>2013</b>: Pos: " + pos_percent + "% , Neg: " + neg_percent + "%"
            })
            .style('left', ( position[0]) + "px");
       });

});