chart.js

var phenologyChart =  Morris.Bar({
                        element:"phenologyChart",
                        data : months,
                        xkey: "mois",
                        ykeys : ["value"],
                        labels: ['Observation(s)'],
                        xLabelAngle: 60,
                        hideHover: 'auto',
                        resize: true,
                        axes: true,
                    });
svgContainer = d3.selectAll("svg");
    svgContainer.append("g")
        .append("text")
            .attr("transform", "rotate(-90)")
            .attr("y", '0%')
            .attr('x', '-15%')
            .attr("dy", ".71em")
            .attr("fill", "#888888")
            .attr("font-size", "10px")
            .style("text-anchor", "end")
            .text("Observations");



rect = d3.selectAll("rect");

            rect.on("mouseover", function(d) {
             d3.select(this).classed("highlight", true);
             d3.select(this).select("text").style("visibility", "visible");

});

            rect.on("mouseout", function() {
    d3.select(this).classed("highlight", false);

});

svgContainer = d3.selectAll("svg");
    svgContainer.append("g")
        .append("text")
            .attr("transform", "rotate(-90)")
            .attr("y", '0%')
            .attr('x', '-15%')
            .attr("dy", ".71em")
            .attr("fill", "#888888")
            .attr("font-size", "10px")
            .style("text-anchor", "end")
            .text("Observations");