# Column groups

# Overview

Columns in Handsontable may be grouped using multiple levels of headers. We refer to them as "nested headers" as they utilize a tree structure.

# Nested headers

The Nested Headers plugin allows creating a nested header structure using the colspan attribute. The header cannot be wider than its parent element, i.e., headers cannot overlap each other.

To make a header that spans across multiple columnns, its corresponding configuration array element should be provided as an object with label and colspan properties. The label property defines the header's label, while the colspan property defines the number of columns that the header should cover.

The maximum value for colspan for nested headers is 1000, meaning that the maximum number of columns that a header can span is 1000. This constraint is based on HTML table specification (opens new window), which sets the limit of colspan to 1000.

# Configuration

nestedHeaders: [
  ['A', { label: 'B', colspan: 8 }, 'C'],
  ['D', { label: 'E', colspan: 4 }, { label: 'F', colspan: 4 }, 'G'],
  ['H', { label: 'I', colspan: 2 }, { label: 'J', colspan: 2 }, { label: 'K', colspan: 2 }, { label: 'L', colspan: 2 }, 'M'],
  ['N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W']
]

# Example

    # Collapsible headers

    The Collapsible Columns plugin enables columns and their headers to be collapsed/expanded.

    This plugin adds multi-column headers which have buttons. Clicking these buttons will collapse or expand all "child" headers, leaving the first one visible.

    The Nested Headers plugin needs to be enabled for this to work properly.

    # Configuration

    To enable the Collapsible Columns plugin, either set the collapsibleColumns property to:

    • true - this will enable the functionality for all multi-column headers, every column with the colspan attribute defined will be extended with the "expand/collapse" button
    • An array of objects containing information specifying which headers should have the "expand/collapse" buttons for example:
    collapsibleColumns: [
      { row: -4, col: 1, collapsible: true }, // Add the button to the 4th-level header of the 1st column - counting from the first table row upwards.
      { row: -3, col: 5, collapsible: true } // Add the button to the 3rd-level header of the 5th column - counting from the first table row upwards.
    ]
    

    # Example