stackedBar
    .tooltipThreshold(600)
    .width(containerWidth)
    .grid('horizontal')
    .isAnimated(true)
    .stackLabel('stack')
    .nameLabel('')
    .valueLabel('views')
    .betweenBarsPadding(0.3)
    .on('customMouseOver', chartTooltip.show)
    .on('customMouseMove', function(dataPoint, topicColorMap, x, y) {
        chartTooltip.update(dataPoint, topicColorMap, x, y);
    })
    .on('customMouseOut', chartTooltip.hide);

container.datum(dataset.data).call(stackedBar);

chartTooltip
    .title('Testing tooltip');

tooltipContainer = d3.select('.metadata-group');
tooltipContainer.datum([]).call(chartTooltip);