Editing bpmn-js demo

<!DOCTYPE html>
<html>

<head>
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta charset="utf-8" />

    <title>bpmn-js demo</title>

    <link rel="stylesheet" href="https://netnr.eu.org/bpmn-js@7.5.0/dist/assets/diagram-js.css" />
    <link rel="stylesheet" href="https://netnr.eu.org/bpmn-js@7.5.0/dist/assets/bpmn-font/css/bpmn.css" />
    <script src="https://netnr.eu.org/bpmn-js@7.5.0/dist/bpmn-modeler.production.min.js"></script>
</head>

<body>
    <div id="canvas"></div>
    <div class="bjs-tool">
        <span data-action="demo">Demo</span>
        <span data-action="import">Import</span>
        <span data-action="export">Export</span>
        <span data-action="svg">SVG</span>
    </div>
</body>

</html>

 html,
 body,
 #canvas {
     height: 100%;
     padding: 0;
     margin: 0;
 }

 .bjs-powered-by {
     display: none;
 }

 .bjs-tool {
     position: fixed;
     top: 1em;
     right: 1em;
 }

 .bjs-tool span {
     cursor: pointer;
     margin-right: 0.5em;
 }

// modeler instance
var bpmnModeler = new BpmnJS({
    container: '#canvas',
    keyboard: {
        bindTo: window
    }
});

bpmnModeler.createDiagram();

document.querySelector('.bjs-tool').addEventListener('click', function (e) {
    var target = e.target, action = target.getAttribute('data-action');
    switch (action) {
        case "demo":
            {
                var diagramUrl = 'https://cdn.staticaly.com/gh/bpmn-io/bpmn-js-examples/dfceecba/starter/diagram.bpmn';
                window.open(diagramUrl, '_blank')
            }
            break;
        case "import":
            {
                var bpmnXML = prompt("bpmnXML");

                try {
                    bpmnModeler.importXML(bpmnXML).then(() => {
                        var canvas = bpmnModeler.get('canvas');

                        // zoom to fit full viewport
                        canvas.zoom('fit-viewport');
                    })
                } catch (err) {
                    console.error(err);
                    alert('import error');
                }
            }
            break;
        case "export":
            {
                bpmnModeler.saveXML({ format: true }).then(res => {
                    console.debug(res.xml)
                    prompt("export", res.xml)
                })
            }
            break;
        case "svg":
            {
                var canvas = bpmnModeler.get('canvas');
                console.debug(canvas._svg)
                prompt("export", canvas._svg.outerHTML)
            }
            break;
    }
})