layerDefaults.bubble.opacity Number (default: 1)

The the opacity of all bubble layers.

Example - set tile layer default opacity

<div id="map"></div>
<script>
    $("#map").kendoMap({
        layerDefaults: {
            bubble: {
                opacity: 0.5
            }
        },
        layers: [{
            type: "bubble",
            dataSource: {
                data: [{
                    "location": [42, 12], "value": 10
                }, {
                    "location": [45, 15], "value": 25
                }]
            }
        }]
    });
</script>