How to display Line Chart dataset point labels with Chart.js?

Question

I have a design requirement to display a line chart with 5 datasets of trends data. Each data value along the stroke lines need to be showing a data value label at its respe

Answer 1

Here's how to do it based on the example provided on github. It looks similar to your solution...

// Define a plugin to provide data labels
Chart.plugins.register({
    afterDatasetsDraw: function(chart, easing) {
        // To only draw at the end of animation, check for easing === 1
        var ctx = chart.ctx;
        chart.data.datasets.forEach(function (dataset, i) {
            var meta = chart.getDatasetMeta(i);
            if (!meta.hidden) {
                meta.data.forEach(function(element, index) {
                    // Draw the text in black, with the specified font
                    ctx.fillStyle = 'rgb(0, 0, 0)';
                    var fontSize = 16;
                    var fontStyle = 'normal';
                    var fontFamily = 'Helvetica Neue';
                    ctx.font = Chart.helpers.fontString(fontSize, fontStyle, fontFamily);
                    // Just naively convert to string for now
                    var dataString = dataset.data[index].toString();
                    // Make sure alignment settings are correct
                    ctx.textAlign = 'center';
                    ctx.textBaseline = 'middle';
                    var padding = 5;
                    var position = element.tooltipPosition();
                    ctx.fillText(dataString, position.x, position.y - (fontSize / 2) - padding);
                });
            }
        });
    }
});

From Code: https://github.com/chartjs/Chart.js/blob/master/samples/advanced/data-labelling.html

Example: http://www.chartjs.org/samples/latest/advanced/data-labelling.html

You can also define plugins inline to the chart instead of globally...

var chart = new Chart(ctx, {
    plugins: [{
        afterDatasetsDraw: ...
    }]
});