This example demonstrate how to load Ogma, load a optional dependency and create an instance of Ogma using SystemJS:

<div id="graph-container" style="position: absolute; width: 800px; height: 600px; border: 1px solid black;"></div>
<script src="path/to/system.js"></script>
<script>
  var Ogma = null;

  SystemJS.import('../../build/ogma.js').then(function (ogmaLibrary) {
    Ogma = ogmaLibrary;

    return SystemJS.import('../../lib/xlsx.min.js');
  }).then(function (xlsx) {
    Ogma.libraries['xlsx'] = xlsx;

    let ogma = new Ogma({
      container: 'graph-container',
      renderer: 'canvas'
    });

    ogma.generate.random().then(function (graph) {
      return ogma.setGraph(graph);
    }).then(function () {
      ogma.view.locateGraph();
      return ogma.layouts.hierarchical();
    }).then(function () {
      return ogma.export.xlsx({filename: 'my-graph.xlsx'});
    });
  });
</script>