hast-util-shift-heading

hast utility to change ranks (also knows as depth or level) of headings.

What is this?
When should I use this?
Install
Use
API
- shiftHeading(tree, shift)
Types
Compatibility
Security
Related
Contribute
License

What is this?

This package is a small utility that rewrites heading ranks relative to a number.

When should I use this?

You can use this package when you have some content, say an article that starts with an h1, but want to display it on a page that uses for example an h1 already as the website name (logo?).

You can use the package hast-util-heading-rank to get the rank of an element.

Install

This package is ESM only. In Node.js (version 16+), install with npm:

npm install hast-util-shift-heading

In Deno with esm.sh:

import {shiftHeading} from 'https://esm.sh/hast-util-shift-heading@4'

In browsers with esm.sh:

<script type="module">
  import {shiftHeading} from 'https://esm.sh/hast-util-shift-heading@4?bundle'
</script>

Use

import {h} from 'hastscript'
import {shiftHeading} from 'hast-util-shift-heading'

const tree = h('main', [
  h('h1', 'Alpha'),
  h('p', 'Bravo'),
  h('h2', 'Charlie'),
  h('p', 'Delta'),
  h('h5', 'Echo'),
  h('p', 'Foxtrot'),
  h('h6', 'Golf')
])

shiftHeading(tree, -1)

console.log(tree)

Yields:

{ type: 'element',
  tagName: 'main',
  properties: {},
  children:
   [ { type: 'element',
       tagName: 'h1',
       properties: {},
       children: [Array] },
     { type: 'element',
       tagName: 'p',
       properties: {},
       children: [Array] },
     { type: 'element',
       tagName: 'h1',
       properties: {},
       children: [Array] },
     { type: 'element',
       tagName: 'p',
       properties: {},
       children: [Array] },
     { type: 'element',
       tagName: 'h4',
       properties: {},
       children: [Array] },
     { type: 'element',
       tagName: 'p',
       properties: {},
       children: [Array] },
     { type: 'element',
       tagName: 'h5',
       properties: {},
       children: [Array] } ] }

API

This package exports the identifier shiftHeading. There is no default export.

`shiftHeading(tree, shift)`

Change the rank of all headings (h1 to h6) in tree.

Mutates the tree. Caps the rank so that shifting would not create invalid headings (so no h0 or h7).

Parameters

tree (Node) — tree to change
shift (number) — non-null finite integer to use to shift ranks

Returns

Nothing (undefined).

Throws

When shift is not a valid non-null finite integer.

Types

This package is fully typed with TypeScript. It exports no additional types.

Compatibility

Projects maintained by the unified collective are compatible with maintained versions of Node.js.

When we cut a new major release, we drop support for unmaintained versions of Node. This means we try to keep the current release line, hast-util-shift-heading@^4, compatible with Node.js 16.

Security

hast-util-shift-heading changes the syntax tree but can only generated headings from h1 through h6. There are no openings for cross-site scripting (XSS) attacks.

hast-util-heading — check if a node is heading content
hast-util-heading-rank — get the rank (or depth, level) of headings

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, organization, or community you agree to abide by its terms.

syntax-tree/hast-util-shift-heading