keep - Turndown

Syntax

turndownService.keep(filter)

Description

Determines which HTML elements should be kept as HTML in the Markdown output instead of being converted. By default, Turndown converts all recognized HTML to Markdown. Use this method to preserve specific elements as raw HTML.

Parameters

string | array | function

required

Specifies which elements to keep as HTML:

String: A single tag name (e.g., 'del')
Array: Multiple tag names (e.g., ['del', 'ins'])
Function: Custom filter function (node, options) => boolean

Returns

TurndownService

Returns the TurndownService instance for method chaining

Examples

Keep Single Element

turndownService.keep('del')
turndownService.turndown('<p>Hello <del>world</del></p>')
// Result: Hello <del>world</del>

Keep Multiple Elements

turndownService.keep(['del', 'ins'])
turndownService.turndown('<p>Hello <del>world</del><ins>World</ins></p>')
// Result: Hello <del>world</del><ins>World</ins>

Keep with Custom Filter

turndownService.keep(function (node) {
  return node.nodeName === 'SPAN' && node.getAttribute('class') === 'keep'
})

turndownService.turndown('<p>Convert <span>this</span> but not <span class="keep">this</span></p>')
// Result: Convert this but not <span class="keep">this</span>

Chaining Keep Calls

turndownService
  .keep('sub')
  .keep('sup')
  .turndown('<p>H<sub>2</sub>O and E=mc<sup>2</sup></p>')
// Result: H<sub>2</sub>O and E=mc<sup>2</sup>

Behavior Details

Block-Level Elements

Block-level elements that are kept will be separated from surrounding content by blank lines:

turndownService.keep('div')
turndownService.turndown('<p>Before</p><div>Middle</div><p>After</p>')
// Result:
// Before
//
// <div>Middle</div>
//
// After

Inline Elements

Inline elements are kept without additional spacing:

turndownService.keep('mark')
turndownService.turndown('<p>This is <mark>highlighted</mark> text</p>')
// Result: This is <mark>highlighted</mark> text

Notes

Returns the instance to enable method chaining
Can be called multiple times; newer filters take precedence
Keep filters are overridden by standard CommonMark rules and added rules
To keep elements handled by default rules, add a custom rule instead
The default keepReplacement function can be customized via constructor options
Block-level kept elements are wrapped with blank lines; inline elements are not

​Syntax

​Description

​Parameters

​Returns

​Examples

​Keep Single Element

​Keep Multiple Elements

​Keep with Custom Filter

​Chaining Keep Calls

​Behavior Details

​Block-Level Elements

​Inline Elements

​Notes