Convert headings to permalinks.

Convert headings to permalinks.

new Permalink(context, options)

Create a Permalink plugin.

If a heading already has an id attribute it is not overwritten.

If the from and to options are given any headings falling outside the range are not modified. If you give from and to values outside the 1-6 range they are clamped. These options are inclusive so setting from: 2 and to: 3 will modify h2 and h3 elements only.

If the to value is less than the from value it is set to equal the from value. You cannot configure the range to select no elements.

The default slug implementation should work well but if you wish to use your own these are the implementation details.

The slug function has the signature:

slug (element, text, seen, options = {})

Where element is the heading DOM element, text is the text for the element that should be used to generate the id, seen is a map that should be used to track duplicate identifiers and options is a reference to the plugin instance. Implementations should respect the lower option.

The slug function must return a unique string identifier for the given element.

Permalink.prototype.sources(file, context, options)

For each HTML file with an AST find matching headings and assign a unique id attribute to the heading.