JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://rawgit.com/nnnick/Chart.js/f3eb6f4a433b4f34a582842dcf7b42f710861a7d/Chart.js"></script>
<canvas id="chart" height="450" width="650"></canvas>

JavaScript

var barChartData = {
    labels: [1, 2, 3, 4, 5, 6, 7],
    datasets: [{
        custom: true,
        label: "My First dataset",
        data: [0, 2, 3, 4, 5, 6, 7],
        backgroundColor: 'red'
    }, {
        label: "My Second dataset",
        data: [3, 4, 5, 6, 7, 1, 2],
        backgroundColor: 'blue'
    }]
};

var ctx = document.getElementById("chart").getContext("2d");
var my_chart = new Chart(ctx, {
    type: "bar",
    data: barChartData
});

$.each(my_chart.data.datasets, function (i, dataset) {
    dataset.metaData[3].custom = {
        backgroundColor: "green"
    };
    dataset.data[3] = 2.5;
});

my_chart.update();