Often there are cases where some values are missing in the data series. Such values are known as null or empty data. The given example shows a JavaScript area graph with a missing/null value. It also includes HTML / JavaScript source code that you can edit in-browser or save to run the chart locally.
window.onload = function() { var chart = new CanvasJS.Chart("chartContainer", { animationEnabled: true, title: { text: "Hourly Average CPU Utilization" }, axisX: { title: "Time" }, axisY: { title: "Percentage", suffix: "%", includeZero: true }, data: [{ type: "line", name: "CPU Utilization", connectNullData: true, //nullDataLineDashType: "solid", xValueType: "dateTime", xValueFormatString: "DD MMM hh:mm TT", yValueFormatString: "#,##0.##\"%\"", dataPoints: [ { x: 1501048673000, y: 35.939 }, { x: 1501052273000, y: 40.896 }, { x: 1501055873000, y: 56.625 }, { x: 1501059473000, y: 26.003 }, { x: 1501063073000, y: 20.376 }, { x: 1501066673000, y: 19.774 }, { x: 1501070273000, y: 23.508 }, { x: 1501073873000, y: 18.577 }, { x: 1501077473000, y: 15.918 }, { x: 1501081073000, y: null }, // Null Data { x: 1501084673000, y: 10.314 }, { x: 1501088273000, y: 10.574 }, { x: 1501091873000, y: 14.422 }, { x: 1501095473000, y: 18.576 }, { x: 1501099073000, y: 22.342 }, { x: 1501102673000, y: 22.836 }, { x: 1501106273000, y: 23.220 }, { x: 1501109873000, y: 23.594 }, { x: 1501113473000, y: 24.596 }, { x: 1501117073000, y: 31.947 }, { x: 1501120673000, y: 31.142 } ] }] }); chart.render(); }
You can connect non-null adjacent dataPoints to show continuity in area or line chart using connectNullData property. The null-data line can further be customized using nullDataLineDashType. Some other customizations include color, fillOpacity, markerType, etc.