Chart.js V2: Add prefix or suffix to tooltip label

Question

In Chart.js V1.0, I would add tooltipTemplate: \"<%if (label){%><%=label %>: <%}%><%= \'€\' + value %>\" to add a euro symbol as prefix

Answer 1

In addition to iecs' answer, if you want to return the exact default text and add some more (like a € sign in your case), use following syntax :

var ctx = $(chartCanvas);
window.chartObject = new Chart(ctx, {
    type: 'bar',
    data: chartData,
    options: {            
        tooltips: {
            callbacks: {
                label: function(tooltipItems, data) {
                    return data.datasets[tooltipItems.datasetIndex].label +': ' + tooltipItems.yLabel + ' €';
                }
            }

        }
    }
});