Hast-util-to-text NPM

hast-util-to-text

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

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.