<div id="chart"></div>
<script>
$("#chart").kendoChart({
    series: [{
        type: "area",
        name: "Series A",
        data: [1, 2, 3]
    }],
    seriesDefaults: {
        legendItem: {
            area: {
                opacity: 0.5
            }
        }
    }
});
</script>