# 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.

# chart.parallelAxes.type

The type of axis. Can be one of `linear`, `logarithmic`, `datetime`, `category` or `treegrid`. Defaults to `treegrid` for Gantt charts, `linear` for other chart types.

In a datetime axis, the numbers are given in milliseconds, and tick marks are placed on appropriate values, like full hours or days. In a category or treegrid axis, the point names of the chart's series are used for categories, if a categories array is not defined.