# 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.sunburst.states.select.halo.opacity

Opacity for the halo unless a specific fill is overridden using the `attributes` setting. Note that Highcharts is only able to apply opacity to colors of hex or rgb(a) formats.