sicos1977 / htmltotext

HTML to Text converter for DotNet

UnDotNet.HtmlToText

HTML to Text converter for DotNet

Ported from node-html-to-text

Advanced converter that parses HTML and returns beautiful text.

Features

• Inline and block-level tags.
• Tables with colspans and rowspans.
• Links with both text and href.
• Word wrapping.
• Unicode support.
• Plenty of customization options.

Installation

Add NuGet package UnDotNet.HtmlToText to your project

Basic Usage

using UnDotNet.HtmlToText;

var text = new HtmlToTextConverter().Convert(html);

With Options

using UnDotNet.HtmlToText;

var options = new HtmlToTextOptions { 
  Wordwrap: 120,
  // ...
};
var text = new HtmlToTextConverter().Convert(html, options);

Example

• Input text: test.html
• Output text: test.txt

General Options

Option	Default	Description
BaseElements		Describes which parts of the input document have to be converted and present in the output text, and in what order.
BaseElements.Selectors	['body']	Elements matching any of provided selectors will be processed and included in the output text, with all inner content. Refer to Supported selectors section below.
BaseElements.OrderBy	'selectors'	'selectors' - arrange base elements in the same order as BaseElements.Selectors array; 'occurrence' - arrange base elements in the order they are found in the input document.
BaseElements.ReturnDomByDefault	true	Convert the entire document if none of provided selectors match.
EncodeCharacters	{}	A dictionary with characters that should be replaced in the output text and corresponding escape sequences.
Formatters	{}	An object with custom formatting functions for specific elements (see Override formatting section below).
Limits		Describes how to limit the output text in case of large HTML documents.
Limits.Ellipsis	'...'	A string to insert in place of skipped content.
Limits.MaxBaseElements	undefined	Stop looking for more base elements after reaching this amount. Unlimited if undefined.
Limits.MaxChildNodes	undefined	Maximum number of child nodes of a single node to be added to the output. Unlimited if undefined.
Limits.MaxDepth	undefined	Stop looking for nodes to add to the output below this depth in the DOM tree. Unlimited if undefined.
Limits.MaxInputLength	16_777_216	If the input string is longer than this value - it will be truncated and a message will be sent to stderr. Ellipsis is not used in this case. Unlimited if undefined.
LongWordSplit		Describes how to wrap long words.
LongWordSplit.WrapCharacters	[]	An array containing the characters that may be wrapped on. Checked in order, search stops once line length requirement can be met.
LongWordSplit.ForceWrapOnLimit	false	Break long words at the line length limit in case no better wrap opportunities found.
PreserveNewlines	false	By default, any newlines \n from the input HTML are collapsed into space as any other HTML whitespace characters. If true, these newlines will be preserved in the output. This is only useful when input HTML carries some plain text formatting instead of proper tags.
Selectors	[]	Describes how different HTML elements should be formatted. See Selectors section below.
WhitespaceCharacters	' \t\r\n\f\u200b'	A string of characters that are recognized as HTML whitespace. Default value uses the set of characters defined in HTML4 standard. (It includes Zero-width space compared to living standard.)
Wordwrap	80	After how many chars a line break should follow. Set to false to disable word-wrapping.

Predefined formatters

Following selectors have a formatter specified as a part of the default configuration. Everything can be overridden, but you don't have to repeat the format or options that you don't want to override. (But keep in mind this is only true for the same selector. There is no connection between different selectors.)

Selector	Default format	Notes
*	inline	Universal selector.
a	anchor
article	block
aside	block
blockquote	blockquote
br	lineBreak
div	block
footer	block
form	block
h1	heading
h2	heading
h3	heading
h4	heading
h5	heading
h6	heading
header	block
hr	horizontalLine
img	image
main	block
nav	block
ol	orderedList
p	paragraph
pre	pre
table	table	Equivalent to block. Use dataTable instead for tabular data.
ul	unorderedList
wbr	wbr

More formatters also available for use:

Format	Description
dataTable	For visually-accurate tables. Note that this might be not search-friendly (output text will look like gibberish to a machine when there is any wrapped cell contents) and also better to be avoided for tables used as a page layout tool.
skip	Skips the given tag with it's contents without printing anything.
blockString	Insert a block with the given string literal (formatOptions.string) instead of the tag.
blockTag	Render an element as HTML block tag, convert it's contents to text.
blockHtml	Render an element with all it's children as HTML block.
inlineString	Insert the given string literal (formatOptions.string) inline instead of the tag.
inlineSurround	Render inline element wrapped with given strings (formatOptions.prefix and formatOptions.suffix).
inlineTag	Render an element as inline HTML tag, convert it's contents to text.
inlineHtml	Render an element with all it's children as inline HTML.

Format options

Following options are available for built-in formatters.

Option	Default	Applies to	Description
LeadingLineBreaks	1, 2 or 3	all block-level formatters	Number of line breaks to separate previous block from this one. Note that N+1 line breaks are needed to make N empty lines.
TrailingLineBreaks	1 or 2	all block-level formatters	Number of line breaks to separate this block from the next one. Note that N+1 line breaks are needed to make N empty lines.
BaseUrl	null	anchor, image	Server host for link href attributes and image src attributes relative to the root (the ones that start with /). For example, with baseUrl = 'http://asdf.com' and <a href='/dir/subdir'>...</a> the link in the text will be http://asdf.com/dir/subdir.
LinkBrackets	['[', ']']	anchor, image	Surround links with these brackets. Set to false or ['', ''] to disable.
PathRewrite	undefined	anchor, image	A function to rewrite link href attributes and image src attributes. Optional second argument is the metadata object. Applied before baseUrl.
HideLinkHrefIfSameAsText	false	anchor	By default links are translated in the following way: <a href='link'>text</a> => becomes => text [link]. If this option is set to true and link and text are the same, [link] will be omitted and only text will be present.
IgnoreHref	false	anchor	Ignore all links. Only process internal text of anchor tags.
NoAnchorUrl	true	anchor	Ignore anchor links (where href='#...').
ItemPrefix	' * '	unorderedList	String prefix for each list item.
Uppercase	true	heading	By default, headings (<h1>, <h2>, etc) are uppercased. Set this to false to leave headings as they are.
Length	undefined	horizontalLine	Length of the line. If undefined then wordwrap value is used. Falls back to 40 if that's also disabled.
TrimEmptyLines	true	blockquote	Trim empty lines from blockquote. While empty lines should be preserved in HTML, space-saving behavior is chosen as default for convenience.
UppercaseHeaderCells	true	dataTable	By default, heading cells (<th>) are uppercased. Set this to false to leave heading cells as they are.
MaxColumnWidth	60	dataTable	Data table cell content will be wrapped to fit this width instead of global wordwrap limit. Set this to undefined in order to fall back to wordwrap limit.
ColSpacing	3	dataTable	Number of spaces between data table columns.
RowSpacing	0	dataTable	Number of empty lines between data table rows.
StringLiteral	''	blockString, inlineString	A string to be inserted in place of a tag.
Prefix	''	inlineSurround	String prefix to be inserted before inline tag contents.
Suffix	''	inlineSurround	String suffix to be inserted after inline tag contents.