# Welcome to the Highcharts Gantt JS (gantt) Options Reference

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

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# tooltip.formatter

Callback function to format the text of the tooltip from scratch. In case of single or shared tooltips, a string should be returned. In case of split tooltips, it should return an array where the first item is the header, and subsequent items are mapped to the points. Return `false` to disable tooltip for a specific point on series.

A subset of HTML is supported. Unless `useHTML` is true, the HTML of the tooltip is parsed and converted to SVG, therefore this isn't a complete HTML renderer. The following HTML tags are supported: `b`, `br`, `em`, `i`, `span`, `strong`. Spans can be styled with a `style` attribute, but only text-related CSS, that is shared with SVG, is handled.

The context of the formatter (since v12) is the Point instance. If the tooltip is shared or split, an array `this.points` contains all points of the hovered x-value.

Common properties from the Point to use in the formatter include:

- Point.percentage: Stacked series and pies only. The point's percentage of the total.

- Point.points: In a shared or split tooltip, this is an array containing all the hovered points.

- this.series: The series object. The series name is available through `this.series.name`.

- this.total: The total value at this point's x value in a stacked series, or the sum of all slices in a pie series.

- this.x: The x value.

- this.y: The y value.