How to set y axis value in vertical bar chart using chart JS

Question

In this vertical bar chart, the y-axis has positive and negative values. I want to use positive integers up and down based on the zero value. I am using version 4.2.1 what should I do? Vertical chart example varMONTHS=["January","February","March","April","May","June","July","

P粉316110779 · Answer

If you only want to change the text of the y-axis labels, you can change them completely by setting the function options.scales.y.ticks.callback, see the documentation and API Reference for details. In your case, to make negative values read as positive, you can use:

callback: function(val){
    return this.getLabelForValue(Math.abs(val));
}

or

callback: function(val){
    return this.getLabelForValue(val).replace(/^-/, '');
}

var ctx = document.getElementById('chart1');
var MONTHS = [
    "January",
    "February",
    "March",
    "April",
    "May",
    "June",
    "July",
    "August",
    "September",
    "October",
    "November",
    "December",
];

var barChartData = {
    labels: ["January", "February", "March", "April", "May", "June", "July"],
    datasets: [
        {
            label: "Dataset 1",
            backgroundColor: 'rgba(255, 201, 14, 1)',
            borderColor: 'rgba(255, 201, 14, 1)',
            borderWidth: 1,
            data: [
                10,
                20,
                30,
                40,
                50
            ],
        },
        {
            label: "Dataset 2",
            backgroundColor: 'rgba(255, 201, 14, 1)',
            borderColor: 'rgba(255, 201, 14, 1)',
            borderWidth: 1,
            data: [
                -100,
                -200,
                -300,
                -400,
                -500
            ],
        },
    ],
};

new Chart(ctx, {
    type: "bar",
    data: barChartData,
    options: {
        responsive: true,
        legend: {
            position: "top",
        },
        title: {
            display: true,
            text: "Chart.js Bar Chart",
        },
        scales:{
            y: {
                ticks: {
                    callback: function(val){
                        return this.getLabelForValue(Math.abs(val));
                        // or: //return this.getLabelForValue(val).replace(/^-/, '');
                    },
                }
            }
        },
    },
});