Welcome to the Highcharts JS (highcharts) Options Reference

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

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The text to announce for speech tracks. Can either be a format string or a function.

If it is a function, it should return the format string to announce. 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.

If it is a format string, in addition to normal string content, format values can be accessed using bracket notation. For example "Value is {point.y}%".

time, point and value are available to the format strings similarly to with functions. Nested properties can be accessed with dot notation, for example "Density: {point.options.custom.density}"