sphinx-js

Why

When you write a JavaScript library, how do you explain it to people? If it's a small project in a domain your users are familiar with, JSDoc's alphabetical list of routines might suffice. But in a larger project, it is useful to intersperse prose with your API docs without having to copy and paste things.

sphinx-js lets you use the industry-leading Sphinx documentation tool with JS projects. It provides a handful of directives, patterned after the Python-centric autodoc ones, for pulling JSDoc-formatted documentation into reStructuredText pages. And, because you can keep using JSDoc in your code, you remain compatible with the rest of your JS tooling, like Google's Closure Compiler.

sphinx-js also works with TypeScript, using the TypeDoc tool in place of JSDoc and emitting all the type information you would expect.

Setup

1. Install JSDoc (or TypeDoc if you're writing TypeScript):

   npm install jsdoc

   or:

   npm install [email protected]

   JSDoc 3.6.3 and 4.0.0 and TypeDoc 0.25--0.28 are known to work.

2. Install sphinx-js, which will pull in Sphinx itself as a dependency:

   pip install sphinx-js

3. Make a documentation folder in your project by running sphinx-quickstart and answering its questions:

   cd my-project
   sphinx-quickstart

   Please enter values for the following settings (just press Enter to
   accept a default value, if one is given in brackets).
   
   Selected root path: .
   
   You have two options for placing the build directory for Sphinx output.
   Either, you use a directory "_build" within the root path, or you separate
   "source" and "build" directories within the root path.
   > Separate source and build directories (y/n) [n]:
   
   The project name will occur in several places in the built documentation.
   > Project name: My Project
   > Author name(s): Fred Fredson
   > Project release []: 1.0
   
   If the documents are to be written in a language other than English,
   you can select a language here by its language code. Sphinx will then
   translate text that it generates into that language.
   
   For a list of supported codes, see
   https://www.sphinx-doc.org/en/master/usage/configuration.html#confval-language.
   > Project language [en]:
   
   Selected root path: .
   
   You have two options for placing the build directory for Sphinx output.
   Either, you use a directory "_build" within the root path, or you separate
   "source" and "build" directories within the root path.
   > Separate source and build directories (y/n) [n]:
   
   The project name will occur in several places in the built documentation.
   > Project name: My Project
   > Author name(s): Fred Fredson
   > Project release []: 1.0
   
   If the documents are to be written in a language other than English,
   you can select a language here by its language code. Sphinx will then
   translate text that it generates into that language.
   
   For a list of supported codes, see
   https://www.sphinx-doc.org/en/master/usage/configuration.html#confval-language.
   > Project language [en]:
   

4. In the generated Sphinx conf.py file, turn on sphinx_js by adding it to extensions:

   extensions = ['sphinx_js']

5. If you want to document TypeScript, add:

   js_language = 'typescript'

   to conf.py as well.

6. If your JS source code is anywhere but at the root of your project, add:

   js_source_path = '../somewhere/else'

   on a line by itself in conf.py. The root of your JS source tree should be where that setting points, relative to the conf.py file.

   The default, ../, works well when there is a docs folder at the root of your project and your source code lives directly inside the root.

7. If you have special JSDoc or TypeDoc configuration, add:

   jsdoc_config_path = '../conf.json'

   to conf.py as well.

8. If you're documenting only JS or TS and no other languages (like C), you can set your "primary domain" to JS in conf.py:

   primary_domain = 'js'

   The domain is js even if you're writing TypeScript. Then you can omit all the "js:" prefixes in the directives below.

History

sphinx-js was created in 2017 by Erik Rose at Mozilla. It was transferred from Mozilla to the Pyodide organization in 2025.

Use

In short, in a Sphinx project, use the following directives to pull in your JSDoc documentation, then tell Sphinx to render it all by running make html in your docs directory. If you have never used Sphinx or written reStructuredText before, here is where we left off in its tutorial. For a quick start, just add things to index.rst until you prove things are working.

autofunction

First, document your JS code using standard JSDoc formatting:

/**
 * Return the ratio of the inline text length of the links in an element to
 * the inline text length of the entire element.
 *
 * @param {Node} node - Types or not: either works.
 * @throws {PartyError|Hearty} Multiple types work fine.
 * @returns {Number} Types and descriptions are both supported.
 */
function linkDensity(node) {
  const length = node.flavors.get("paragraphish").inlineLength;
  const lengthWithoutLinks = inlineTextLength(
    node.element,
    (element) => element.tagName !== "A",
  );
  return (length - lengthWithoutLinks) / length;
}

Then, reference your documentation using sphinx-js directives. Our directives work much like Sphinx's standard autodoc ones. You can specify just a function's name:

.. js:autofunction:: someFunction

and a nicely formatted block of documentation will show up in your docs.

You can also throw in your own explicit parameter list, if you want to note optional parameters:

.. js:autofunction:: someFunction(foo, bar[, baz])

Parameter properties and destructuring parameters also work fine, using standard JSDoc syntax:

/**
 * Export an image from the given canvas and save it to the disk.
 *
 * @param {Object} options Output options
 * @param {string} options.format The output format (``jpeg``,  ``png``, or
 *     ``webp``)
 * @param {number} options.quality The output quality when format is
 *     ``jpeg`` or ``webp`` (from ``0.00`` to ``1.00``)
 */
function saveCanvas({ format, quality }) {
  // ...
}

Extraction of default parameter values works as well. These act as expected, with a few caveats:

/**
 * You must declare the params, even if you have nothing else to say, so
 * JSDoc will extract the default values.
 *
 * @param [num]
 * @param [str]
 * @param [bool]
 * @param [nil]
 */
function defaultsDocumentedInCode(
  num = 5,
  str = "true",
  bool = true,
  nil = null,
) {}

/**
 * JSDoc guesses types for things like "42". If you have a string-typed
 * default value that looks like a number or boolean, you'll need to
 * specify its type explicitly. Conversely, if you have a more complex
 * value like an arrow function, specify a non-string type on it so it
 * isn't interpreted as a string. Finally, if you have a disjoint type like
 * {string|Array} specify string first if you want your default to be
 * interpreted as a string.
 *
 * @param {function} [func=() => 5]
 * @param [str=some string]
 * @param {string} [strNum=42]
 * @param {string|Array} [strBool=true]
 * @param [num=5]
 * @param [nil=null]
 */
function defaultsDocumentedInDoclet(func, strNum, strBool, num, nil) {}

You can even add additional content. If you do, it will appear just below any extracted documentation:

.. js:autofunction:: someFunction

    Here are some things that will appear...

    * Below
    * The
    * Extracted
    * Docs

    Enjoy!

js:autofunction has one option, :short-name:, which comes in handy for chained APIs whose implementation details you want to keep out of sight. When you use it on a class method, the containing class won't be mentioned in the docs, the function will appear under its short name in indices, and cross references must use the short name as well (:func:someFunction``):

.. js:autofunction:: someClass#someFunction
   :short-name:

autofunction can also be used on callbacks defined with the @callback tag.

There is experimental support for abusing autofunction to document @typedef tags as well, though the result will be styled as a function, and @property tags will fall misleadingly under an "Arguments" heading. Still, it's better than nothing until we can do it properly.

If you are using typedoc, it also is possible to destructure keyword arguments by using the @destructure tag:

/**
* @param options
* @destructure options
*/
function f({x , y } : {
    /** The x value */
    x : number,
    /** The y value */
    y : string
}){ ... }

will be documented like:

options.x (number) The x value
options.y (number) The y value

autoclass

We provide a js:autoclass directive which documents a class with the concatenation of its class comment and its constructor comment. It shares all the features of js:autofunction and even takes the same :short-name: flag, which can come in handy for inner classes. The easiest way to use it is to invoke its :members: option, which automatically documents all your class's public methods and attributes:

.. js:autoclass:: SomeEs6Class(constructor, args, if, you[, wish])
   :members:

You can add private members by saying:

.. js:autoclass:: SomeEs6Class
   :members:
   :private-members:

Privacy is determined by JSDoc @private tags or TypeScript's private keyword.

Exclude certain members by name with :exclude-members::

.. js:autoclass:: SomeEs6Class
   :members:
   :exclude-members: Foo, bar, baz

Or explicitly list the members you want. We will respect your ordering.

.. js:autoclass:: SomeEs6Class
   :members: Qux, qum

When explicitly listing members, you can include * to include all unmentioned members. This is useful to have control over ordering of some elements, without having to include an exhaustive list.

.. js:autoclass:: SomeEs6Class
   :members: importMethod, *, uncommonlyUsedMethod

Finally, if you want full control, pull your class members in one at a time by embedding js:autofunction or js:autoattribute:

.. js:autoclass:: SomeEs6Class

   .. js:autofunction:: SomeEs6Class#someMethod

   Additional content can go here and appears below the in-code comments,
   allowing you to intersperse long prose passages and examples that you
   don't want in your code.

autoattribute

This is useful for documenting public properties:

class Fnode {
  constructor(element) {
    /**
     * The raw DOM element this wrapper describes
     */
    this.element = element;
  }
}

And then, in the docs:

.. autoclass:: Fnode

   .. autoattribute:: Fnode#element

This is also the way to document ES6-style getters and setters, as it omits the trailing () of a function. The assumed practice is the usual JSDoc one: document only one of your getter/setter pair:

class Bing {
  /** The bong of the bing */
  get bong() {
    return this._bong;
  }

  set bong(newBong) {
    this._bong = newBong * 2;
  }
}

And then, in the docs:

.. autoattribute:: Bing#bong

automodule

This directive documents all exports on a module. For example:

.. js:automodule:: package.submodule

autosummary

This directive should be paired with an automodule directive (which may occur in a distinct rst file). It makes a summary table with links to the entries generated by the automodule directive. Usage:

.. js:automodule:: package.submodule

Dodging Ambiguity With Pathnames

If you have same-named objects in different files, use pathnames to disambiguate them. Here's a particularly long example:

.. js:autofunction:: ./some/dir/some/file.SomeClass#someInstanceMethod.staticMethod~innerMember

You may recognize the separators #.~ from JSDoc namepaths; they work the same here.

For conciseness, you can use any unique suffix, as long as it consists of complete path segments. These would all be equivalent to the above, assuming they are unique within your source tree:

innerMember
staticMethod~innerMember
SomeClass#someInstanceMethod.staticMethod~innerMember
some/file.SomeClass#someInstanceMethod.staticMethod~innerMember

Things to note:

• We use simple file paths rather than JSDoc's module: prefix or TypeDoc's external: or module: ones.

• We use simple backslash escaping exclusively rather than switching escaping schemes halfway through the path; JSDoc itself is headed that way as well. The characters that need to be escaped are #.~(/, though you do not need to escape the dots in a leading ./ or ../. A really horrible path might be:

  some/path\ with\ spaces/file.topLevelObject#instanceMember.staticMember\(with\(parens
  

• Relative paths are relative to the js_source_path specified in the config. Absolute paths are not allowed.

Behind the scenes, sphinx-js will change all separators to dots so that:

• Sphinx's "shortening" syntax works: ":func:`~InwardRhs.atMost`" prints as merelyatMost(). (For now, you should always use dots rather than other namepath separators: #~.)
• Sphinx indexes more informatively, saying methods belong to their classes.

Saving Keystrokes By Setting The Primary Domain

To save some keystrokes, you can set:

primary_domain = 'js'

in conf.py and then use autofunction rather than js:autofunction.

TypeScript: Getting Superclass and Interface Links To Work

To have a class link to its superclasses and implemented interfaces, you'll need to document the superclass (or interface) somewhere using js:autoclass or js:class and use the class's full (but dotted) path when you do:

.. js:autoclass:: someFile.SomeClass

Unfortunately, Sphinx's ~ syntax doesn't work in these spots, so users will see the full paths in the documentation.

TypeScript: Cross references

TypeScript types will be converted to cross references. To render cross references, you can define a hook in conf.py called ts_type_xref_formatter. It should take two arguments: the first argument is the sphinx confix, and the second is an sphinx_js.ir.TypeXRef object. This has a name field and two variants:

• a sphinx_js.ir.TypeXRefInternal with fields path and kind
• a sphinx_js.ir.TypeXRefExternal with fields name, package, sourcefilename and qualifiedName

The return value should be restructured text that you wish to be inserted in place of the type. For example:

def ts_xref_formatter(config, xref):
    if isinstance(xref, TypeXRefInternal):
        name = rst.escape(xref.name)
        return f":js:{xref.kind}:`{name}`"
    else:
        # Otherwise, don't insert a xref
        return xref.name

Configuration Reference

js_language

Use 'javascript' or 'typescript' depending on the language you use. The default is 'javascript'.

js_source_path

A list of directories to scan (non-recursively) for JS or TS source files, relative to Sphinx's conf.py file. Can be a string instead if there is only one. If there is more than one, root_for_relative_js_paths must be specified as well. Defaults to ../.

root_for_relative_js_paths

Relative JS entity paths are resolved relative to this path. Defaults to js_source_path if not present.

jsdoc_config_path

A conf.py-relative path to a JSDoc config file, which is useful if you want to specify your own JSDoc options, like recursion and custom filename matching. If using TypeDoc, you can also point to a typedoc.json file.

jsdoc_tsconfig_path

If using TypeDoc, specify the path of tsconfig.json file

ts_type_xref_formatter

A function for formatting TypeScript type cross references. See the "TypeScript: Cross references" section below.

ts_type_bold

Make all TypeScript types bold if true.

ts_sphinx_js_config

A link to a TypeScript config file.

The ts_sphinx_js_config file

This file should be a TypeScript module. It's executed in a context where it can import typedoc and sphinx_js. These functions take TypeDoc IR objects as arguments. Since the TypeDoc IR is unstable, this config may often break when switching TypeDoc versions. However, these hooks are very powerful so using them may be worthwhile anyways. This API is experimental and may change in the future.

For an example, you can see Pyodide's config file here.

This file should export a config object with some of the three following functions:

• shouldDestructureArg: (param: ParameterReflection) => boolean

This function takes a ParameterReflection and decides if it should be destructured. If so, it's equivalent to putting a @destructure tag for the argument. For example:

function shouldDestructureArg(param: ParameterReflection) {
  return param.name === "options";
}

• preConvert?: (app: Application) => Promise<void>;

This hook is called with the TypeDoc application as argument before the TypeScript files are parsed. For example, it can be used to add extra TypeDoc plugins.

• postConvert: (app: Application, project: ProjectReflection, typeDocToIRMap: Map<DeclarationReflection, TopLevelIR>) => void

This hook is called after the sphinx_js IR is created. It can be used to modify the IR arbitrarily. It is very experimental and subject to breaking changes.

For example, this postConvert hook removes the constructor from classes marked with @hideconstructor.

function postConvert(app, project, typeDocToIRMap) {
  for (const [key, value] of typeDocToIRMap.entries()) {
    if (
      value.kind === "class" &&
      value.modifier_tags.includes("@hideconstructor")
    ) {
      value.constructor_ = null;
    }
  }
}

To use it, you'll also need to add a tag definition for @hideconstructor to your tsdoc.json file:

{
  "tagDefinitions": [
    {
      "tagName": "@hideconstructor",
      "syntaxKind": "modifier"
    }
  ]
}

This postConvert hook hides external attributes and functions from the documentation:

function postConvert(app, project, typeDocToIRMap) {
  for (const [key, value] of typeDocToIRMap.entries()) {
    if (value.kind === "attribute" || value.kind === "function") {
      value.is_private = key.flags.isExternal || key.flags.isPrivate;
    }
  }
}

How sphinx-js finds typedoc / jsdoc

1. If the environment variable SPHINX_JS_NODE_MODULES is defined, it is expected to point to a node_modules folder in which typedoc / jsdoc is installed.

2. If SPHINX_JS_NODE_MODULES is not defined, we look in the directory of conf.py for a node_modules folder in which typedoc / jsdoc. If this is not found, we look for a node_modules folder in the parent directories until we make it to the root of the file system.

3. We check if typedoc / jsdoc are on the PATH, if so we use that.

4. If none of the previous approaches located typedoc / jsdoc we raise an error.

Example

A good example using most of sphinx-js's functionality is the Fathom documentation. A particularly juicy page is https://mozilla.github.io/fathom/ruleset.html. Click the "View page source" link to see the raw directives.

For a TypeScript example, see the Pyodide api docs.

ReadTheDocs is the canonical hosting platform for Sphinx docs and now supports sphinx-js. Put this in the .readthedocs.yml file at the root of your repo:

python:
  install:
    - requirements: docs/requirements.txt

Then put the version of sphinx-js you want in docs/requirements.txt. For example:

sphinx-js==3.1.2

Caveats

• We don't understand the inline JSDoc constructs like {@link foo}; you have to use Sphinx-style equivalents for now, like :js:func:foo (or simply `:func:`foo if you have set primary_domain = 'js' in conf.py.
• So far, we understand and convert the JSDoc block tags @param, @returns, @throws, @example (without the optional <caption>), @deprecated, @see, and their synonyms. Other ones will go poof into the ether.

Tests

Run the tests using nox, which will also install JSDoc and TypeDoc at pinned versions:

pip install nox
nox

Provenance

sphinx-js was originally written and maintained by Erik Rose and various contributors within and without the Mozilla Corporation and Foundation. See CONTRIBUTORS for details.