0
The method ". getElementById('value'). value" shows the value of div as null
<html>
<head>
<link rel="stylesheet" href="demos.css" type="text/css" media="screen" />
<script src="/sistema/jquery/plugins/RGraph/libraries/RGraph.common.core.js" ></script>
<script src="/sistema/jquery/plugins/RGraph/libraries/RGraph.common.dynamic.js" ></script>
<script src="/sistema/jquery/plugins/RGraph/libraries/RGraph.common.tooltips.js" ></script>
<script src="/sistema/jquery/plugins/RGraph/libraries/RGraph.line.js" ></script>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
<script type="text/javascript" src="http://www.google.com/jsapi"></script>
<script type="text/javascript">
    google.load("jquery", "1.3.2", {uncompressed:true});
</script>
<script type="text/javascript" src="json.class.js"></script>
<!--[if lt IE 9]><script src="../excanvas/excanvas.js"></script><![endif]-->
<p style="margin-left:50em;"><title>Cotação USD x BRL</title></p>
<meta name="robots" content="noindex,nofollow" />
<meta name="Descrição" content="Cotação do Dolar de Acordo com o Real" />
</head>
<body>
<h2></h2>
<canvas id="cvs" width="900" height="300">[No canvas support]</canvas>
<script>
    $(document).ready(function ()
    {
        var data     = [document.getElementById('valor').value];
        var tooltips = [];
        //[2.59,2.60,2.40,2.67,1.78];
        // Create the tooltips
        for (var i=0; i<data.length; i+=1) {
            tooltips[i] = '1 USD = ' + String(data[i] + ' Reais')
        }
        var line = new RGraph.Line({
            id: 'cvs',
            data: data,
            options: {
                tooltips: {
                    self: tooltips,
                    highlight: false
                },
                colors: ['#058DC7'],
                filled: true,
                fillstyle: 'rgba(229,243,249,0.5)',
                tickmarks: 'filledcircle',
                background: {
                    grid: {
                        vlines: false,
                        border: false,
                        autofit: {
                            numhlines: 10
                        }
                    }
                },
                shadow: false,
                linewidth: 3,
                gutter: {
                    left: 50,
                    right: 20
                },
                numxticks: 0,
                ylabels: {
                    count: 5
                },
                axis: {
                    color: '#aaa'
                },
                text: {
                    color: '#aaa'
                },
                labels: ['21/01','22/01','23/01','24/01','25/01']
            }
        })
        RGraph.ISOLD ? line.draw() : line.trace2();
    })
</script>
<div id="valor"></div>
<div id="label"></div>
javascript-preferred
– nardo_bruxo