# JS API Reference

# Welcome to the Highcharts JS Options Reference

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

Feel free to search this API through the search bar or the navigation tree in the sidebar.

# plotOptions.variablepie.tooltip.dateTimeLabelFormats

For series on a datetime axes, the date format in the tooltip's header will by default be guessed based on the closest data points. This member gives the default string representations used for each unit. For an overview of the replacement codes, see dateFormat.