# 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.

# series.funnel3d.tooltip.headerFormat

The HTML of the tooltip header line. Variables are enclosed by curly brackets. Available variables are `point.key`, `series.name`, `series.color` and other members from the `point` and `series` objects. The `point.key` variable contains the category name, x value or datetime string depending on the type of axis. For datetime axes, the `point.key` date format can be set using `tooltip.xDateFormat`.