JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.2.1/Chart.min.js"></script>
<canvas id="canvas" height="100"></canvas>

JavaScript

var ctx = document.getElementById("canvas");

Chart.pluginService.register({
    afterDraw: function(chart) {
        if (typeof chart.config.options.lineAt != 'undefined') {
        	var lineAt = chart.config.options.lineAt;
            var ctxPlugin = chart.chart.ctx;
            var xAxe = chart.scales[chart.config.options.scales.xAxes[0].id];
            var yAxe = chart.scales[chart.config.options.scales.yAxes[0].id];
           	
            // I'm not good at maths
            // So I couldn't find a way to make it work ...
            // ... without having the `min` property set to 0
            if(yAxe.min != 0) return;
            
            ctxPlugin.strokeStyle = "red";
        	ctxPlugin.beginPath();
            lineAt = (lineAt - yAxe.min) * (100 / yAxe.max);
            lineAt = (100 - lineAt) / 100 * (yAxe.height) + yAxe.top;
            ctxPlugin.moveTo(xAxe.left, lineAt);
            ctxPlugin.lineTo(xAxe.right, lineAt);
            ctxPlugin.stroke();
        }
    }
});

var myChart = new Chart(ctx, {
    type: 'bar',
    data: {
        labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
        datasets: [{
            label: '# of Votes',
            data: [12, 19, 3, 5, 2, 3],
            backgroundColor: [
                'rgba(255, 99, 132, 0.2)',
                'rgba(54, 162, 235, 0.2)',
                'rgba(255, 206, 86, 0.2)',
                'rgba(75, 192, 192, 0.2)',
                'rgba(153, 102, 255, 0.2)',
                'rgba(255, 159, 64, 0.2)'
            ],
            borderColor: [
                'rgba(255,99,132,1)',
                'rgba(54, 162, 235, 1)',
                'rgba(255, 206, 86, 1)',
                'rgba(75, 192, 192, 1)',
                'rgba(153, 102, 255, 1)',
                'rgba(255, 159, 64, 1)'
            ],
            borderWidth: 1
        }]
    },
    options: {
        lineAt: 14,
        scales: {
            yAxes: [{
                ticks: {
                    min: 0
  ...