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html-to-text

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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.

Changelog

Available here: CHANGELOG.md

Version 6 contains a ton of changes, so it worth to take a look.

Version 7 contains an important change for custom formatters.

Version 8 brings the selectors support to greatly increase the flexibility but that also changes some things introduced in version 6. Base element(s) selection also got important changes.

Installation

npm install html-to-text

Usage

Convert a single document:

const { convert } = require('html-to-text');
// There is also an alias to `convert` called `htmlToText`.

const html = '<h1>Hello World</h1>';
const text = convert(html, {
  wordwrap: 130
});
console.log(text); // Hello World

Configure html-to-text once for batch processing:

const { compile } = require('html-to-text');

const convert = compile({
  wordwrap: 130
});

const htmls = [
  '<h1>Hello World!</h1>',
  '<h1>こんにちは世界!</h1>',
  '<h1>Привет, мир!</h1>'
];
const texts = htmls.map(convert);
console.log(texts.join('\n'));
// Hello World!
// こんにちは世界!
// Привет, мир!

Options

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.
decodeOptions { isAttributeValue: false, strict: false } Text decoding options given to he.decode. For more informations see the he module.
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 null or false to disable word-wrapping.

Deprecated or removed options

Old option Depr. Rem. Instead use
baseElement 8.0 baseElements: { selectors: [ 'body' ] }
format 6.0 The way formatters are written has changed completely. New formatters have to be added to the formatters option, old ones can not be reused without rewrite. See new instructions below.
hideLinkHrefIfSameAsText 6.0 9.0 selectors: [ { selector: 'a', options: { hideLinkHrefIfSameAsText: true } } ]
ignoreHref 6.0 9.0 selectors: [ { selector: 'a', options: { ignoreHref: true } } ]
ignoreImage 6.0 9.0 selectors: [ { selector: 'img', format: 'skip' } ]
linkHrefBaseUrl 6.0 9.0 selectors: [
{ selector: 'a', options: { baseUrl: 'https://example.com' } },
{ selector: 'img', options: { baseUrl: 'https://example.com' } }
]
noAnchorUrl 6.0 9.0 selectors: [ { selector: 'a', options: { noAnchorUrl: true } } ]
noLinkBrackets 6.0 9.0 selectors: [ { selector: 'a', options: { noLinkBrackets: true } } ]
returnDomByDefault 8.0 baseElements: { returnDomByDefault: true }
singleNewLineParagraphs 6.0 9.0 selectors: [
{ selector: 'p', options: { leadingLineBreaks: 1, trailingLineBreaks: 1 } },
{ selector: 'pre', options: { leadingLineBreaks: 1, trailingLineBreaks: 1 } }
]
tables 8.0 selectors: [ { selector: 'table.class#id', format: 'dataTable' } ]
tags 8.0 See Selectors section below.
unorderedListItemPrefix 6.0 9.0 selectors: [ { selector: 'ul', options: { itemPrefix: ' * ' } } ]
uppercaseHeadings 6.0 9.0 selectors: [
{ selector: 'h1', options: { uppercase: false } },
...
{ selector: 'table', options: { uppercaseHeaderCells: false } }
]

Other things deprecated:

  • fromString method;
  • positional arguments in BlockTextBuilder methods (in case you have written some custom formatters for version 6.0).

Selectors

Some example:

const { convert } = require('html-to-text');

const html = '<a href="/page.html">Page</a><a href="!#" class="button">Action</a>';
const text = convert(html, {
  selectors: [
    { selector: 'a', options: { baseUrl: 'https://example.com' } },
    { selector: 'a.button', format: 'skip' }
  ]
});
console.log(text); // Page [https://example.com/page.html]

Selectors array is our loose approximation of a stylesheet.

  • highest specificity selector is used when there are multiple matches;
  • the last selector is used when there are multiple matches of equal specificity;
  • all entries with the same selector value are merged (recursively) at the compile stage, in such way so the last defined properties a kept and the relative order of unique selectors is kept;
  • user-defined entries are appended after predefined entries;
  • Every unique selector must have format value specified (at least once);
  • unlike in CSS, values from different matched selectors are NOT merged at the convert stage. Single best match is used instead (that is the last one of those with highest specificity).

To achieve the best performance when checking each DOM element against provided selectors, they are compiled into a decision tree. But it is also important how you choose selectors. For example, div#id is much better than #id - the former will only check divs for the id while the latter has to check every element in the DOM.

Supported selectors

html-to-text relies on parseley and selderee packages for selectors support.

Following selectors can be used in any combinations:

  • * - universal selector;
  • div - tag name;
  • .foo - class name;
  • #bar - id;
  • [baz] - attribute presence;
  • [baz=buzz] - attribute value (with any operators and also quotes and case sensitivity modifiers);
  • + and > combinators (other combinators are not supported).

You can match <p style="...; display:INLINE; ...">...</p> with p[style*="display:inline"i] for example.

Predefined formatters

Following selectors have a formatter specified as a part of the default configuration. Everything can be overriden, 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:

  • 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 - as the name implies it skips the given tag with it's contents without printing anything.
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.
Keep in mind that baseUrl should not end with a /.
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='#...').
noLinkBrackets false anchor Don't print brackets around links.
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.

Override formatting

This is significantly changed in version 6.

formatters option is an object that holds formatting functions. They can be assigned to format different elements in the selectors array.

Each formatter is a function of four arguments that returns nothing. Arguments are:

  • elem - the HTML element to be processed by this formatter;
  • walk - recursive function to process the children of this element. Called as walk(elem.children, builder);
  • builder - BlockTextBuilder object. Manipulate this object state to build the output text;
  • formatOptions - options that are specified for a tag, along with this formatter (Note: if you need general html-to-text options - they are accessible via builder.options).

Custom formatter example:

const { convert } = require('html-to-text');

const html = '<foo>Hello World</foo>';
const text = convert(html, {
  formatters: {
    // Create a formatter.
    'fooBlockFormatter': function (elem, walk, builder, formatOptions) {
      builder.openBlock({ leadingLineBreaks: formatOptions.leadingLineBreaks || 1 });
      walk(elem.children, builder);
      builder.addInline('!');
      builder.closeBlock({ trailingLineBreaks: formatOptions.trailingLineBreaks || 1 });
    }
  },
  selectors: [
    // Assign it to `foo` tags.
    {
      selector: 'foo',
      format: 'fooBlockFormatter',
      options: { leadingLineBreaks: 1, trailingLineBreaks: 1 }
    }
  ]
});
console.log(text); // Hello World!

Refer to built-in formatters for more examples. The easiest way to write your own is to pick an existing one and customize.

Refer to BlockTextBuilder for available functions and arguments.

Note: BlockTextBuilder got some important changes in the version 7. Positional arguments are deprecated and formatters written for the version 6 have to be updated accordingly in order to keep working after next major update.

Command Line Interface

It is possible to use html-to-text as command line interface. This allows an easy validation of your generated text and the integration in other systems that does not run on node.js.

html-to-text uses stdin and stdout for data in and output. So you can use html-to-text the following way:

cat example/test.html | html-to-text > test.txt

There also all options available as described above. You can use them like this:

cat example/test.html | html-to-text --tables=#invoice,.address --wordwrap=100 > test.txt

The tables option has to be declared as comma separated list without whitespaces.

Example

Contributors

License

MIT License