Extend bar chart on Chart JS 2 into a new type of Chart

Question

I\'m actualy using Chart JS 2.0.1 to draw charts on a page.

My customers asked me to add a line in a bar chart so that they can see the limit they can\'t go over. Like

Answer 1

This is helpful but I found it not that optimized to add new Dataset just for a line that is actually not a data.

I finally suceeded in creating the new type that extend the bar type and add a line if the value is provided.

// Store the original Draw function
var originalLineDraw = Chart.controllers.bar.prototype.draw;
// extend the new type
Chart.helpers.extend(Chart.controllers.bar.prototype, {
    draw: function () {
    // use the base draw function
    originalLineDraw.apply(this, arguments);

    // get chart and context
    var chart = this.chart;
    var ctx = chart.chart.ctx;

    // get lineAtValue value
    var value = chart.config.lineAtValue;

    // stop if it doesn't exist
    if (typeof value === "undefined") {
        return;
    }

    // draw the line
    var xaxis = chart.scales['x-axis-0'];
    var yaxis = chart.scales['y-axis-0'];
    ctx.save();
    ctx.beginPath();
    ctx.moveTo(xaxis.left, yaxis.getPixelForValue(value));
    ctx.strokeStyle = '#ff0000';
    ctx.lineTo(xaxis.right, yaxis.getPixelForValue(value));
    ctx.stroke();
    ctx.restore();

    }
});

But thank you for your help =)