Bounding box
From JSXGraph Wiki
Instead of supplying values for originX, originY, unitX, unitY, we can alternatively provide a bounding box to specify the dimensions for the drawing panel defined by
<div id="jxgbox" class="jxgbox" style="width:500px; height:500px;"></div>
The JavaScript code
var board = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-5,10,5,-2], keepaspectratio: true, axis:true});
sets the vertical and horizontal units and the position of the origin such that the upper left corner of the drawing panel has position (-5,10) and the lower right corner of the drawing panel has position (5,-2).
The source code of the page looks like this:
<link rel="stylesheet" type="text/css" href="http://jsxgraph.uni-bayreuth.de/distrib/jsxgraph.css" />
<script type="text/javascript" src="http://jsxgraph.uni-bayreuth.de/distrib/jsxgraphcore.js"></script>
<div id="jxgbox" class="jxgbox" style="width:500px; height:500px;"></div>
<script type="text/javascript">
var board = JXG.JSXGraph.initBoard('jxgbox', {boundingbox:[-5,10,5,-2], axis:true});
</script>