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RGraph is a JavaScript charts library based on HTML5 SVG and canvas. RGraph is mature (over 17 years old) and has a wealth of features making it an ideal choice to use for showing charts on your website.

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Get the latest version of RGraph (version 6.21, 10th April 2025) from the download page. You can read the changelog here. There's also older versions available, minified files and links to cdnjs.com hosted libraries.

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Hello,
I should draw the graph and based on the input data updating the graph with the new data, and this works but draw the new bars on top of the old ones without gradually removing the bars of the previous graph, without updating the graph. How can I solve?
Thanks

You can use the RGraph.clear() function to clear the canvas before drawing a second time. For example:

var canvas = myObject.canvas;

RGraph.clear(canvas);

PS. If you want an animated change then the Bar chart supports this by supplying the new data to the grow() function. There's an example here:

https://codepen.io/rgraph/pen/yLgQmvw

The code of which is this:

bar = new RGraph.Bar({
id:'cvs',
data: [8,4,6,3,5,4,2],
options: {
     yaxis:false,
     xaxis:false,
     backgroundGridVlines: false,
     backgroundGridBorder: false,
     yaxisScaleMax: 20
}
}).grow();

setInterval(function ()
{
    // count,min,max[,decimals]
    newData = RGraph.arrayRandom(7,0,20);

    bar.grow({data: newData});
}, 2000);

Richard

I tried to write:

var canvas = document.getElementById ('cvs');
RGraph.clear (canvas);

before redrawing the graph the second time but I don't update the graph.

You then need to redraw the chart with either an animation function or the draw function like this:

var canvas = document.getElementById ('cvs'); // Or myObject.canvas works too

RGraph.clear (canvas); // Clear the canvas
myObject.draw();     // Redraw the chart

I tried but don't work.
I share the whole function so that you can check where the error is:


function mostraNascondiGrafico(arrayValGraficoAsseX, arrayDateLabelAsseX, arrayLimiti) {






    if ($('#divGraph').is(':visible')) {
     $("#divGraph").hide();
     $("#buttMostrNascGrafico").text("MOSTRA GRAFICO");
     }
     else {

     $("#divGraph").show();
     $("#buttMostrNascGrafico").text("NASCONDI GRAFICO");
    


//I entered the suggested lines here, is that correct?
    var canvas =document.getElementById('cvs');
    RGraph.clear(canvas);




    
    bar = new RGraph.Bar({
        id: 'cvs',
    
        data: arrayValGraficoAsseX,


        options: {

            yaxisScaleMax: 80,
            backgroundGridVlines: false,
            backgroundGridBorder: false,
            backgroundGridColor: '#999',
            
            xaxisLabels: arrayDateLabelAsseX,

            marginLeft: 55,
            marginRight: 55,
            marginBottom: 75,

            colors: ['Gradient(#A18AC5:#D1AAF5)'],
            textColor: '#ccc',
            xaxisTickmarksCount: 0,
            xaxis: false,
            yaxis: false,
            shadowColor: 'black',
            shadowOffsetx: 0,
            shadowOffsety: 0,
            shadowBlur: 15,
            colorsStroke: 'rgba(0,0,0,0)',
            combinedEffect: 'wave',
            combinedEffectOptions: '{frames: 30}'

        }
    });


    line = new RGraph.Line({
        id: 'cvs',
        data: arrayLimiti,
        options: {
            yaxisScaleMax: 80,
            xaxis: false,
            yaxis: false,
            backgroundGrid: false,
            colors: ['#d00'],
            yaxisPosition: 'right',
            textColor: '#ccc',
            marginLeft: 45,
            marginRight: 45,
            tickmarksStyle: null,
            spline: true,
            combinedEffect: 'trace',
            textSize: 18
        }
    });

    combo = new RGraph.CombinedChart([bar, line]).draw();

    // Poiche la classe combinata disattiva le etichette del grafico a linee,
    // le riattiva
    line.set({
        yaxisScale: true
    });

    RGraph.redraw();

    // Aggiunge alcune capacita di risposta al grafico a barre
    bar.responsive([


         {maxWidth: null, width: 1400, height: 500, options: {textSize: 18, marginInner: 20}},
        {maxWidth: 1600, width: 1400, height: 500, options: {textSize: 12, marginInner: 7}}



    ]);

    
    line.responsive([
        {maxWidth: null, width: 1400, height: 500, options: {textSize: 18, marginInner: 45, linewidth: 7}},
        {maxWidth: 1600, width: 1400, height: 500, options: {textSize: 12, marginInner: 20, linewidth: 5}}

        
    ]);




    }
}

solved, I used the reset () function instead of clear ()