Answer by mpen for Chart.js v2 hide dataset labels

You can also put the tooltip onto one line by removing the "title":

this.chart = new Chart(ctx, {
    type: this.props.horizontal ? 'horizontalBar' : 'bar',
    options: {
        legend: {
            display: false,
        },
        tooltips: {
            callbacks: {
                label: tooltipItem => `${tooltipItem.yLabel}: ${tooltipItem.xLabel}`, 
                title: () => null,
            }
        },
    },
});

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