# Table of Contents

## Summary

The Table of Contents extension generates a Table of Contents from a Markdown document and adds it into the resulting HTML document.

This extension is included in the standard Markdown library.

## Syntax

By default, all headers will automatically have unique `id` attributes generated based upon the text of the header. Note this example, in which all three headers would have the same `id`:

    #Header
    #Header
    #Header

Results in:

    <h1 id="header">Header</h1>
    <h1 id="header_1">Header</h1>
    <h1 id="header_2">Header</h1>

Place a marker in the document where you would like the Table of Contents to appear. Then, a nested list of all the headers in the document will replace the marker. The marker defaults to `[TOC]` so the following document:

    [TOC]

    # Header 1

    ## Header 2

would generate the following output:

    <div class="toc">
      <ul>
        <li>
          <a href="#header-1">Header 1</a>
          <ul>
            <li><a href="#header-2">Header 2</a></li>
          </ul>
        </li>
      </ul>
    </div>
    <h1 id="header-1">Header 1</h1>
    <h2 id="header-2">Header 2</h2>

Regardless of whether a `marker` is found in the document (or disabled), the Table of Contents is available as an attribute (`toc`) on the Markdown class. This allows one to insert the Table of Contents elsewhere in their page template. For example:

    >>> md = markdown.Markdown(extensions=['toc'])
    >>> html = md.convert(text)
    >>> page = render_some_template(context={'body': html, 'toc': md.toc})

The `toc_tokens` attribute is also available on the Markdown class and contains a nested list of dict objects. For example, the above document would result in the following object at `md.toc_tokens`:

    [
        {
            'level': 1,
            'id': 'header-1',
            'name': 'Header 1',
            'html': 'Header 1',
            'data-toc-label': '',
            'children': [
                {'level': 2, 'id': 'header-2', 'name': 'Header 2', 'children':[]}
            ]
        }
    ]

Note that the `level` refers to the `hn` level. In other words, `<h1>` is level `1` and `<h2>` is level `2`, etc. Be aware that improperly nested levels in the input may result in odd nesting of the output.

`name` is the sanitized value which would also be used as a label for the HTML version of the Table of Contents. `html` contains the fully rendered HTML content of the heading and has not been sanitized in any way. This may be used with your own custom sanitation to create custom table of contents.

### Custom Labels

In most cases, the text label in the Table of Contents should match the text of the header. However, occasionally that is not desirable. In that case, if this extension is used in conjunction with the Attribute Lists Extension and a `data-toc-label` attribute is defined on the header, then the contents of that attribute will be used as the text label for the item in the Table of Contents. For example, the following Markdown:

    [TOC]

    # Functions

    ## `markdown.markdown(text [, **kwargs])` { #markdown data-toc-label='markdown.markdown' }

would generate the following output:

    <div class="toc">
      <ul>
        <li>
          <a href="#functions">Functions</a>
          <ul>
            <li><a href="#markdown">markdown.markdown</a></li>
          </ul>
        </li>
      </ul>
    </div>
    <h1 id="functions">Functions</h1>
    <h2 id="markdown"><code>markdown.markdown(text [, **kwargs])</code></h2>

Notice that the text in the Table of Contents is much cleaner and easier to read in the context of a Table of Contents. The `data-toc-label` is not included in the HTML header element. Also note that the ID was manually defined in the attribute list to provide a cleaner URL when linking to the header. If the ID is not manually defined, it is always derived from the text of the header, never from the `data-toc-label` attribute.

The value of the `data-toc-label` attribute is sanitized and stripped of any HTML tags. However, `toc_tokens` will contain the raw content under `data-toc-label`.

## Usage

See Extensions for general extension usage. Use `toc` as the name of the extension.

See the Library Reference for information about configuring extensions.

The following options are provided to configure the output:

- `marker`: Text to find and replace with the Table of Contents. Defaults to `[TOC]`.

  Set to an empty string to disable searching for a marker, which may save some time, especially on long documents.

- `title`: Title to insert in the Table of Contents’ `<div>`. Defaults to `None`.

- `title_class`: CSS class used for the title contained in the Table of Contents. Defaults to `toctitle`.

- `toc_class`: CSS class(es) used for the `<div>` containing the Table of Contents. Defaults to `toc`.

- `anchorlink`: Set to `True` to cause all headers to link to themselves. Default is `False`.

- `anchorlink_class`: CSS class(es) used for the link. Defaults to `toclink`.

- `permalink`: Set to `True` or a string to generate permanent links at the end of each header. Useful with Sphinx style sheets.

  When set to `True` the paragraph symbol (¶ or “`&para;`”) is used as the link text. When set to a string, the provided string is used as the link text.

- `permalink_class`: CSS class(es) used for the link. Defaults to `headerlink`.

- `permalink_title`: Title attribute of the permanent link. Defaults to `Permanent link`.

- `permalink_leading`: Set to `True` if the extension should generate leading permanent links. Default is `False`.

  Leading permanent links are placed at the start of the header tag, before any header content. The default `permalink` behavior (when `permalink_leading` is unset or set to `False`) creates trailing permanent links, which are placed at the end of the header content.

- `baselevel`: Base level for headers. Defaults to `1`.

  The `baselevel` setting allows the header levels to be automatically adjusted to fit within the hierarchy of your HTML templates. For example, suppose the Markdown text for a page should not contain any headers higher than level 3 (`<h3>`). The following will accomplish that:

      >>>  text = '''
      ... #Some Header
      ... ## Next Level'''
      >>> from markdown.extensions.toc import TocExtension
      >>> html = markdown.markdown(text, extensions=[TocExtension(baselevel=3)])
      >>> print html
      <h3 id="some_header">Some Header</h3>
      <h4 id="next_level">Next Level</h4>'

- `slugify`: Callable to generate anchors.

  Default: `markdown.extensions.toc.slugify`

  In order to use a different algorithm to define the id attributes, define and pass in a callable which takes the following two arguments:

  - `value`: The string to slugify.
  - `separator`: The Word Separator.

  The callable must return a string appropriate for use in HTML `id` attributes.

  An alternate version of the default callable supporting Unicode strings is also provided as `markdown.extensions.toc.slugify_unicode`.

- `separator`: Word separator. Character which replaces white space in id. Defaults to “`-`”.

- `toc_depth` Define the range of section levels to include in the Table of Contents. A single integer (`b`) defines the bottom section level (`<h1>..<hb>`) only. A string consisting of two digits separated by a hyphen in between (`"2-5"`), define the top (`t`) and the bottom (`b`) (`<ht>..<hb>`). Defaults to `6` (bottom).

  When used with conjunction with `baselevel`, this parameter will not take the fitted hierarchy from `baselevel` into account. That is, if both `toc_depth` and `baselevel` are `3`, then only the highest level will be present in the table. If you set `baselevel` to `3` and `toc_depth` to `"2-6"`, the first headline will be `<h3>` and so still included in the Table of Contents. To exclude this first level, you have to set `toc_depth` to `"4-6"`.

A trivial example:

    markdown.markdown(some_text, extensions=['toc'])