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hast-util-to-text

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hast utility to get the plain-text value of a node.

Contents

What is this?

This package is a utility that takes a hast node and gets its plain-text value. It is like the DOMs Node#innerText, which is a bit nicer than Node#textContent, because this turns <br> elements into line breaks and uses '\t' (tabs) between table cells.

There are some small deviations from the spec, because the DOM has knowledge of associated CSS, and can take into account that elements have display: none or text-transform association with them, and this utility can’t do that.

When should I use this?

This is a small utility that is useful when you want a plain-text version of a node that is close to how it’s “visible” to users.

This utility is similar to hast-util-to-string, which is simpler, and more like the Node#textContent algorithm discussed above.

There is also a package hast-util-from-text, which sort of does the inverse: it takes a string, sets that as text on the node, while turning line endings into <br>s

Install

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

npm install hast-util-to-text

In Deno with esm.sh:

import {toText} from 'https://esm.sh/hast-util-to-text@4'

In browsers with esm.sh:

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

Use

import {h} from 'hastscript'
import {toText} from 'hast-util-to-text'

const tree = h('div', [
  h('h1', {hidden: true}, 'Alpha.'),
  h('article', [
    h('p', ['Bravo', h('br'), 'charlie.']),
    h('p', 'Delta echo \t foxtrot.')
  ])
])

console.log(toText(tree))

Yields:

Bravo
charlie.

Delta echo foxtrot.

API

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

toText(tree[, options])

Get the plain-text value of a node.

Parameters
  • tree (Node) — tree to turn into text
  • options (Options, optional) — configuration
Returns

Serialized tree (string).

Algorithm
  • if tree is a comment, returns its value
  • if tree is a text, applies normal whitespace collapsing to its value, as defined by the CSS Text spec
  • if tree is a root or element, applies an algorithm similar to the innerText getter as defined by HTML
Notes

👉 Note: the algorithm acts as if tree is being rendered, and as if we’re a CSS-supporting user agent, with scripting enabled.

  • if tree is an element that is not displayed (such as a head), we’ll still use the innerText algorithm instead of switching to textContent
  • if descendants of tree are elements that are not displayed, they are ignored
  • CSS is not considered, except for the default user agent style sheet
  • a line feed is collapsed instead of ignored in cases where Fullwidth, Wide, or Halfwidth East Asian Width characters are used, the same goes for a case with Chinese, Japanese, or Yi writing systems
  • replaced elements (such as audio) are treated like non-replaced elements

Options

Configuration (TypeScript type).

Fields
  • whitespace (Whitespace, default: 'normal') — default whitespace setting to use

Whitespace

Valid and useful whitespace values (from CSS) (TypeScript type).

Type
type Whitespace = 'normal' | 'nowrap' | 'pre' | 'pre-wrap'

Types

This package is fully typed with TypeScript. It exports the additional types Options and Whitespace.

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-to-text@^4, compatible with Node.js 16.

Security

hast-util-to-text does not change the syntax tree so there are no openings for cross-site scripting (XSS) attacks.

Related

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.

License

MIT © Titus Wormer