ChartJS - Different color per data point

With recent versions of chart.js I would recommend doing this with scriptable options.

Scriptable options give you an easy way to vary the style of a dataset property (e.g. line point colour) dynamically according to some function you provide. Your function is passed a 'context' object that tells it the index and value of the point etc. (see below).

Most chart properties can be scripted; the dataset properties for each chart type tell you the exact list (e.g. see here for line chart).

Here is how you might use scriptable options on a line chart (based on the example in the docs). On this chart negative data points are shown in red, and positive ones in alternating blue/green:

window.myChart = Chart.Line(ctx, {
    data: {
        labels: x_data,
        datasets: [
            {
                data: y_data,
                label: "Test Data",
                borderColor: "#3e95cd",
                fill: false,
                pointBackgroundColor: function(context) {
                    var index = context.dataIndex;
                    var value = context.dataset.data[index];
                    return value < 0 ? 'red' :  // draw negative values in red
                        index % 2 ? 'blue' :    // else, alternate values in blue and green
                            'green';
                }
            }
        ],
    }
});

The context object passed to your function can have the following properties. Some of these won't be present for certain types of entity, so test before use.

• chart: the associated chart
• dataIndex: index of the current data
• dataset: dataset at index datasetIndex
• datasetIndex: index of the current dataset
• hover: true if hovered

In updating to version 2.2.2 of ChartJS, I found that the accepted answer no longer works. The datasets will take an array holding styling information for the properties. In this case:

var pointBackgroundColors = [];
var myChart = new Chart($('#myChart').get(0).getContext('2d'), {
    type: 'line',
    data: {
        datasets: [
            {
                data: dataPoints,
                pointBackgroundColor: pointBackgroundColors
            }
        ]
    }
});

for (i = 0; i < myChart.data.datasets[0].data.length; i++) {
    if (myChart.data.datasets[0].data[i] > 100) {
        pointBackgroundColors.push("#90cd8a");
    } else {
        pointBackgroundColors.push("#f58368");
    }
}

myChart.update();

I found this looking through the samples for ChartJS, specifically this one: "Different Point Sizes Example"