# Welcome to the Highcharts Gantt JS (gantt) Options Reference

These pages outline the chart configuration options, and the methods and properties of Highcharts objects.

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# series.xrange.sonification.contextTracks.activeWhen

Define a condition for when a track should be active and not.

Can either be a function callback or a configuration object.

If a function is used, it should return a `boolean` for whether or not the track should be active. The function is called for each audio event, and receives a parameter object with `time`, and potentially `point` and `value` properties depending on the track. `point` is available if the audio event is related to a data point. `value` is available if the track is used as a context track, and `valueInterval` is used.