mdast-util-heading-range
mdast utility to find headings and replace the content in their section.
Contents
What is this?
This package is a utility that lets you find a certain heading, then takes the content in their section (from it to the next heading of the same or lower depth), and calls a given handler with the result, so that you can change or replace things.
When should I use this?
This utility is typically useful when you have certain sections that can be generated. For example, this utility is used by remark-toc to update the above Contents heading.
A similar package, mdast-zone, does the same but uses comments to mark the start and end of sections.
Install
This package is ESM only. In Node.js (version 12.20+, 14.14+, or 16.0+), install with npm:
npm install mdast-util-heading-range
In Deno with esm.sh:
import {headingRange} from 'https://esm.sh/mdast-util-heading-range@3'
In browsers with esm.sh:
<script type="module">
import {headingRange} from 'https://esm.sh/mdast-util-heading-range@3?bundle'
</script>
Use
Say we have the following file, example.md:
# Foo
Bar.
# Baz
…and a module example.js:
import {read} from 'to-vfile'
import {remark} from 'remark'
import {headingRange} from 'mdast-util-heading-range'
const file = await remark()
.use(myPluginThatReplacesFoo)
.process(await read('example.md'))
console.log(String(file))
/** @type {import('unified').Plugin<[], import('mdast').Root>} */
function myPluginThatReplacesFoo() {
return (tree) => {
headingRange(tree, 'foo', (start, nodes, end) => [
start,
{type: 'paragraph', children: [{type: 'text', value: 'Qux.'}]},
end
])
}
}
…now running node example.js yields:
# Foo
Qux.
# Baz
API
This package exports the identifier headingRange. There is no default export.
headingRange(tree, test|options, handler)
Search tree (Node) and transform a section with handler (Function).
options
Configuration (optional).
options.test
Heading to look for (string, RegExp, Function). When string, wrapped in new RegExp('^(' + value + ')$', 'i'); when RegExp, wrapped in function (value) {expression.test(value)}
options.ignoreFinalDefinitions
Ignore trailing definitions otherwise in the section (boolean, default: false).
function test(value, node)
Function called for each heading with its content (string) and node itself (Heading) to check if it’s the one to look for.
Returns
Whether to use this heading (boolean).
function handler(start, nodes, end, info)
Callback called when a range is found.
Parameters
Arguments.
start
Start of range (Heading).
nodes
Nodes between start and end (Array<Node>).
end
End of range, if any (Node?).
info
Extra info (Object):
parent(Node) — parent of the rangestart(number) — index ofstartinparentend(number?) — index ofendinparent
Types
This package is fully typed with TypeScript. This package exports the types Handler, Options, TestFunction, Test, and ZoneInfo.
Compatibility
Projects maintained by the unified collective are compatible with all maintained versions of Node.js. As of now, that is Node.js 12.20+, 14.14+, and 16.0+. Our projects sometimes work with older versions, but this is not guaranteed.
Security
Improper use of handler can open you up to a cross-site scripting (XSS) attack as the value it returns is injected into the syntax tree. This can become a problem if the tree is later transformed to hast. The following example shows how a script is injected that could run when loaded in a browser.
/** @type {import('mdast-util-heading-range').Handler} */
function handler(start, nodes, end) {
return [start, {type: 'html', value: '<script>alert(1)</script>'}, end]
}
Yields:
# Foo
<script>alert(1)</script>
# Baz
Either do not use user input in handler or use hast-util-santize.
Related
mdast-zone— similar but uses comments to mark the start and end of sections
Contribute
See contributing.md in syntax-tree/.github for ways to get started. See support.md for ways to get help.
This project has a code of conduct. By interacting with this repository, organisation, or community you agree to abide by its terms.