[Solved]-How To Show Tooltip In Sparkline Chart From Code-Highcharts

The tooltip refresh method accepts the first argument only as an array of points:

    if (thechart.renderTo.tagName == 'TD') {
        var theSeries = thechart.series[0]
        thechart.tooltip.refresh([theSeries.points[0]]);
    }

Next problem here is outside option for the tooltip, which causes another error. I recommend you to use:

td,
th {
    ...
    overflow: visible !important;
}

Live demo: https://jsfiddle.net/BlackLabel/qx31oa7m/

API: https://api.highcharts.com/highcharts/tooltip.outside