This uses the relatively new addition to canvas from the canvas v5 specification - native dotted and dashed lines. As browsers add support you will be able to use the option in them but currently (May 2013) it's only supported in Chrome.
obj.Set('background.grid.dashed', true); obj.Set('background.grid.dotted', true);This goes in the documents header:
<script src="RGraph.common.core.js"></script> <script src="RGraph.line.js"></script>Put this where you want the chart to show up:
<canvas id="cvs1" width="600" height="250">[No canvas support]</canvas> <canvas id="cvs2" width="600" height="250">[No canvas support]</canvas>This is the code that generates the chart:
<script> line1 = new RGraph.Line({ id: 'cvs1', data: [4,5,3,8,4,9,6,5,3], options: { xaxisLabels: ['Mal', 'Barry', 'Gary', 'Neil', 'Kim', 'Pete', 'Lou', 'Fred', 'Joe'], backgroundGridDashed: true, title: 'A dashed background grid', titleSize: 16, titleBold: true, marginTop: 35 } }).draw(); line2 = new RGraph.Line({ id: 'cvs2', data: [4,5,3,8,4,9,6,5,3], options: { xaxisLabels: ['Mal', 'Barry', 'Gary', 'Neil', 'Kim', 'Pete', 'Lou', 'Fred', 'Joe'], title: 'A dotted background grid', titleSize: 16, titleBold: true, backgroundGridDotted: true, marginTop: 35 } }).draw(); </script>