site/node_modules/micromark-extension-gfm-footnote/lib/html.js

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/**
* @typedef {import('micromark-util-types').HtmlExtension} HtmlExtension
*/
/**
* @callback BackLabelTemplate
* Generate a back label dynamically.
*
* For the following markdown:
*
* ```markdown
* Alpha[^micromark], bravo[^micromark], and charlie[^remark].
*
* [^remark]: things about remark
* [^micromark]: things about micromark
* ```
*
* This function will be called with:
*
* * `0` and `0` for the backreference from `things about micromark` to
* `alpha`, as it is the first used definition, and the first call to it
* * `0` and `1` for the backreference from `things about micromark` to
* `bravo`, as it is the first used definition, and the second call to it
* * `1` and `0` for the backreference from `things about remark` to
* `charlie`, as it is the second used definition
* @param {number} referenceIndex
* Index of the definition in the order that they are first referenced,
* 0-indexed.
* @param {number} rereferenceIndex
* Index of calls to the same definition, 0-indexed.
* @returns {string}
* Back label to use when linking back from definitions to their reference.
*/
/**
* @typedef Options
* Configuration.
* @property {string | null | undefined} [clobberPrefix='user-content-']
* Prefix to use before the `id` attribute on footnotes to prevent them from
* *clobbering* (default: `'user-content-'`).
*
* Pass `''` for trusted markdown and when you are careful with
* polyfilling.
* You could pass a different prefix.
*
* DOM clobbering is this:
*
* ```html
* <p id="x"></p>
* <script>alert(x) // `x` now refers to the `p#x` DOM element</script>
* ```
*
* The above example shows that elements are made available by browsers, by
* their ID, on the `window` object.
* This is a security risk because you might be expecting some other variable
* at that place.
* It can also break polyfills.
* Using a prefix solves these problems.
* @property {string | null | undefined} [label='Footnotes']
* Textual label to use for the footnotes section (default: `'Footnotes'`).
*
* Change it when the markdown is not in English.
*
* This label is typically hidden visually (assuming a `sr-only` CSS class
* is defined that does that) and so affects screen readers only.
* If you do have such a class, but want to show this section to everyone,
* pass different attributes with the `labelAttributes` option.
* @property {string | null | undefined} [labelAttributes='class="sr-only"']
* Attributes to use on the footnote label (default: `'class="sr-only"'`).
*
* Change it to show the label and add other attributes.
*
* This label is typically hidden visually (assuming an `sr-only` CSS class
* is defined that does that) and so affects screen readers only.
* If you do have such a class, but want to show this section to everyone,
* pass an empty string.
* You can also add different attributes.
*
* > 👉 **Note**: `id="footnote-label"` is always added, because footnote
* > calls use it with `aria-describedby` to provide an accessible label.
* @property {string | null | undefined} [labelTagName='h2']
* HTML tag name to use for the footnote label element (default: `'h2'`).
*
* Change it to match your document structure.
*
* This label is typically hidden visually (assuming a `sr-only` CSS class
* is defined that does that) and so affects screen readers only.
* If you do have such a class, but want to show this section to everyone,
* pass different attributes with the `labelAttributes` option.
* @property {BackLabelTemplate | string | null | undefined} [backLabel]
* Textual label to describe the backreference back to references (default:
* `defaultBackLabel`).
*
* The default value is:
*
* ```js
* function defaultBackLabel(referenceIndex, rereferenceIndex) {
* return (
* 'Back to reference ' +
* (referenceIndex + 1) +
* (rereferenceIndex > 1 ? '-' + rereferenceIndex : '')
* )
* }
* ```
*
* Change it when the markdown is not in English.
*
* This label is used in the `aria-label` attribute on each backreference
* (the `` links).
* It affects users of assistive technology.
*/
import {normalizeIdentifier} from 'micromark-util-normalize-identifier'
import {sanitizeUri} from 'micromark-util-sanitize-uri'
const own = {}.hasOwnProperty
/** @type {Options} */
const emptyOptions = {}
/**
* Generate the default label that GitHub uses on backreferences.
*
* @param {number} referenceIndex
* Index of the definition in the order that they are first referenced,
* 0-indexed.
* @param {number} rereferenceIndex
* Index of calls to the same definition, 0-indexed.
* @returns {string}
* Default label.
*/
export function defaultBackLabel(referenceIndex, rereferenceIndex) {
return (
'Back to reference ' +
(referenceIndex + 1) +
(rereferenceIndex > 1 ? '-' + rereferenceIndex : '')
)
}
/**
* Create an extension for `micromark` to support GFM footnotes when
* serializing to HTML.
*
* @param {Options | null | undefined} [options={}]
* Configuration (optional).
* @returns {HtmlExtension}
* Extension for `micromark` that can be passed in `htmlExtensions` to
* support GFM footnotes when serializing to HTML.
*/
export function gfmFootnoteHtml(options) {
const config = options || emptyOptions
const label = config.label || 'Footnotes'
const labelTagName = config.labelTagName || 'h2'
const labelAttributes =
config.labelAttributes === null || config.labelAttributes === undefined
? 'class="sr-only"'
: config.labelAttributes
const backLabel = config.backLabel || defaultBackLabel
const clobberPrefix =
config.clobberPrefix === null || config.clobberPrefix === undefined
? 'user-content-'
: config.clobberPrefix
return {
enter: {
gfmFootnoteDefinition() {
const stack = this.getData('tightStack')
stack.push(false)
},
gfmFootnoteDefinitionLabelString() {
this.buffer()
},
gfmFootnoteCallString() {
this.buffer()
}
},
exit: {
gfmFootnoteDefinition() {
let definitions = this.getData('gfmFootnoteDefinitions')
const footnoteStack = this.getData('gfmFootnoteDefinitionStack')
const tightStack = this.getData('tightStack')
const current = footnoteStack.pop()
const value = this.resume()
if (!definitions) {
this.setData('gfmFootnoteDefinitions', (definitions = {}))
}
if (!own.call(definitions, current)) definitions[current] = value
tightStack.pop()
this.setData('slurpOneLineEnding', true)
// “Hack” to prevent a line ending from showing up if were in a definition in
// an empty list item.
this.setData('lastWasTag')
},
gfmFootnoteDefinitionLabelString(token) {
let footnoteStack = this.getData('gfmFootnoteDefinitionStack')
if (!footnoteStack) {
this.setData('gfmFootnoteDefinitionStack', (footnoteStack = []))
}
footnoteStack.push(normalizeIdentifier(this.sliceSerialize(token)))
this.resume() // Drop the label.
this.buffer() // Get ready for a value.
},
gfmFootnoteCallString(token) {
let calls = this.getData('gfmFootnoteCallOrder')
let counts = this.getData('gfmFootnoteCallCounts')
const id = normalizeIdentifier(this.sliceSerialize(token))
/** @type {number} */
let counter
this.resume()
if (!calls) this.setData('gfmFootnoteCallOrder', (calls = []))
if (!counts) this.setData('gfmFootnoteCallCounts', (counts = {}))
const index = calls.indexOf(id)
const safeId = sanitizeUri(id.toLowerCase())
if (index === -1) {
calls.push(id)
counts[id] = 1
counter = calls.length
} else {
counts[id]++
counter = index + 1
}
const reuseCounter = counts[id]
this.tag(
'<sup><a href="#' +
clobberPrefix +
'fn-' +
safeId +
'" id="' +
clobberPrefix +
'fnref-' +
safeId +
(reuseCounter > 1 ? '-' + reuseCounter : '') +
'" data-footnote-ref="" aria-describedby="footnote-label">' +
String(counter) +
'</a></sup>'
)
},
null() {
const calls = this.getData('gfmFootnoteCallOrder') || []
const counts = this.getData('gfmFootnoteCallCounts') || {}
const definitions = this.getData('gfmFootnoteDefinitions') || {}
let index = -1
if (calls.length > 0) {
this.lineEndingIfNeeded()
this.tag(
'<section data-footnotes="" class="footnotes"><' +
labelTagName +
' id="footnote-label"' +
(labelAttributes ? ' ' + labelAttributes : '') +
'>'
)
this.raw(this.encode(label))
this.tag('</' + labelTagName + '>')
this.lineEndingIfNeeded()
this.tag('<ol>')
}
while (++index < calls.length) {
// Called definitions are always defined.
const id = calls[index]
const safeId = sanitizeUri(id.toLowerCase())
let referenceIndex = 0
/** @type {Array<string>} */
const references = []
while (++referenceIndex <= counts[id]) {
references.push(
'<a href="#' +
clobberPrefix +
'fnref-' +
safeId +
(referenceIndex > 1 ? '-' + referenceIndex : '') +
'" data-footnote-backref="" aria-label="' +
this.encode(
typeof backLabel === 'string'
? backLabel
: backLabel(index, referenceIndex)
) +
'" class="data-footnote-backref">↩' +
(referenceIndex > 1
? '<sup>' + referenceIndex + '</sup>'
: '') +
'</a>'
)
}
const reference = references.join(' ')
let injected = false
this.lineEndingIfNeeded()
this.tag('<li id="' + clobberPrefix + 'fn-' + safeId + '">')
this.lineEndingIfNeeded()
this.tag(
definitions[id].replace(/<\/p>(?:\r?\n|\r)?$/, function ($0) {
injected = true
return ' ' + reference + $0
})
)
if (!injected) {
this.lineEndingIfNeeded()
this.tag(reference)
}
this.lineEndingIfNeeded()
this.tag('</li>')
}
if (calls.length > 0) {
this.lineEndingIfNeeded()
this.tag('</ol>')
this.lineEndingIfNeeded()
this.tag('</section>')
}
}
}
}
}