Brush function for d3.js that redraws the vertical axis based on the range of data currently shown

brush_redraw_vertical_axis.js

function brush() {
    // Use x.domain to filter the data, then find the max and min duration of this new set, and set y.domain to that
    x.domain(brush.empty() ? x2.domain() : brush.extent());
    var dataFiltered = data.filter(function(d, i) {
        if ( (d.date >= x.domain()[0]) && (d.date <= x.domain()[1]) ) {
            return this;
        }
    })
    var buildersFiltered = color.domain().map(function(name) {
        return {
            name: name,
            values: dataFiltered.map(function(d) {
                return {date: d.date, count: +d[name]};
            })
        };
    });

    y.domain([
        d3.min(buildersFiltered, function(c) { return d3.min(c.values, function(v) { return v.count; }); }),
        d3.max(buildersFiltered, function(c) { return d3.max(c.values, function(v) { return v.count; }); })
    ]);

    focus.selectAll(".builder").select("path").attr("d", function(d) { return line(d.values); })
    focus.select(".x.axis").call(xAxis);
    focus.select(".y.axis").call(yAxis);


    // focus.select("path").attr("d", area);
    // focus.select(".x.axis").call(xAxis);
}