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Node bindings for LibTidy aka TidyLib aka TidyHTML library


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This package provides bindings to libtidy which can be used to parse and tidy up HTML 5. The library is built as a native node extension, compiled from sources shipped with the package. Precompiled libraries are available for many common platforms, and will get installed automatically if available. So you don't have to have the HTML Tidy package installed on your system.


  • tidy-html5 has libtidy compiled to JavaScript using emscripten. It is likely more portable, but at the cost of performance. Only supports synchroneous operation.
  • tidy and tidy2 also provide bindings for libtidy, but they expect the library and its header files to be installed on the system. Only supports synchroneous operation.
  • htmltidy and htmltidy2 use the command line tool to tidy up html, so they incur some process creation overhead. The binaries for the most common platforms are shipped with the package, but other platforms are not supported. This approach requires no build tools, though. Only supports asynchroneous operation.

The project will try to provide drop-in replacements for these libraries, so that people can easily compare implementations. At the moment, the tidy method shared with the htmltidy modules is the only such replacement which has been implemented.


The project aims to provide fine-grained access to a growing set of library functions, with a rather direct mapping between JavaScript and C functions. On the other hand, the project offers high-level functions to easily deal with common workflows.

Callback convention

Most asynchroneous operations in this library take an optional callback with the conventional node signature cb(err, res). If no callback is provided, a promise is returned which either resolves to res or gets rejected with err. In the case of a serious error, err will contain an exception providing details about the problem. In less severe situations, err will be null (in case of a callback) and res will be an object containing several properties:

  • errlog contains the error messages generated during the run, formatted as a string including a trailing newline.
  • output contains the output buffer if output was generated. The property is unset if generating output was not part of the method in question, or null if no output was generated due to errors.

Other useful properties may be added in the future.


High-level functions automate the most common workflows.

tidyBuffer(document, [options,] callback)

The document is assumed to be a buffer or a string. Anything else will be converted to a string and then turned into a buffer. options is an optional dictionary of options, see the section on options for details. callback follows the convention described above.

Basic workflow

The type libtidy.TidyDoc is the central object for dealing with the library at a low level. Such an object will hold a configuration and be able to process one input file at a time, while multiple such objects can deal with multiple inputs simultaneously using an independent configuration for each of them.

The basic workflow consists of these four steps executed on such an object:

Step C API Synchroneous JavaScript Asynchroneous JavaScript
1. tidyParseBuffer(doc,&buf) doc.parseBufferSync(buf) doc.parseBuffer(buf,cb)
2. tidyCleanAndRepair(doc) doc.cleanAndRepairSync() doc.cleanAndRepair(cb)
3. tidyRunDiagnostics(doc) doc.runDiagnosticsSync() doc.runDiagnostics(cb)
4. tidySaveBuffer(doc,&buf) doc.saveBufferSync() doc.saveBuffer(cb)

Most synchroneous functions take no argument and return any diagnostic messages generated in the process. The first of the methods takes a buffer as an argument, and the last returns the resulting output buffer. The asynchroneous methods take a callback function as last argument, following the convention described above.


For the list of available options, please refer to the Quick Reference.

There are various ways to operate on options. Each time an option is identified, the library offers several choices: the option may be identified by name (i.e. a string), by id (i.e. an integer) or by a TidyOption object. When using a string, you may choose between the original hyphenated name, a version where hyphens are replaced by underscores, or a camelCase version. So alt-text, alt_text and altText all describe the same option.

The lowest level of option access are the optGet(key) and optSet(key, value) methods of the TidyDoc object. These encompass the whole tidyOpt{Get,Set}{Value,Int,Bool} family of functions in the C API.

The methods getOption(key) and getOptionList() return a single TidyOption object resp. the list of all available options. Each such option object contains getters for the following properties: name, category, id, type, readOnly, default, pickList.

The options property of each TidyDoc object can be used for elegant high-level access to all the options. It provides a dictionary of getter/setter pairs, which can be used to directly inspect modify each of the options. The keys in this dictionary use the underscore notation. The options property itself is implemented using a getter/setter pair, and the setter takes its argument and configures all its keys-value pairs. In this case you again have full choice of naming convention. So one way to configure a document object would be this:

var libtidy = require("libtidy");
var doc = libtidy.TidyDoc();
doc.options = {
  forceOutput = true,
  output_xhtml = false,


The following lists the full public interface of the package. Details on each item can be found in the API documentation.

TypeScript support

This library ships with a .d.ts declaration for TypeScript users.

For contributors: part of the declaration is generated by util/gen-typescript-decl.js (executed by npm prepublish / pretest hook).


The project itself uses the MIT license. For the license of the underlying library, please see its license file


To clone the project and start developing run the following commands

git clone --recursive
cd node-libtidy
npm install
npm test

If you want to update to the latest version of libtidy, you can execute

cd tidy-html5
git checkout master
echo "Bump libtidy to `git describe --tags`" | tee ../commit_message.tmp
cd ..
git add tidy-html5
npm install
npm test
git commit -e -F commit_message.tmp
rm commit_message.tmp

You may want to substitute some other branch name instead of master, e.g. in order to get the latest version of some release branch.

If you think that using a given version is important not just for yourself, but for others as well, then please open an issue and request a release using that version. If the version in question is not the latest release, then please provide some reason why that particular version would be useful.