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`.consthtml='<h1>Hello World</h1>';consttext=convert(html,{wordwrap: 130});console.log(text);// Hello World
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 information 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.
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;
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 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:
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 /.
linkBrackets
['[', ']']
anchor, image
Surround links with these brackets. Set to false or ['', ''] to disable.
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.
Deprecated format options
Old option
Applies to
Depr.
Rem.
Instead use
noLinkBrackets
anchor
8.1
linkBrackets: false
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');consthtml='<foo>Hello World</foo>';consttext=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:
请发表评论