hast-util-find-and-replace

hast utility to find and replace things.

Contents

• What is this?
• When should I use this?
• Install
• Use
• API
  • defaultIgnore
  • findAndReplace(tree, list[, options])
  • Find
  • FindAndReplaceList
  • FindAndReplaceTuple
  • Options
  • RegExpMatchObject
  • Replace
  • ReplaceFunction
• Types
• Compatibility
• Security
• Related
• Contribute
• License

What is this?

This package is a utility that lets you find patterns (string, RegExp) in text and replace them with nodes (such as elements). It’s aware of HTML (such as ignoring <style> and <script> by default).

When should I use this?

This utility is typically useful when you have regexes and want to modify hast. One example is when you have some form of “mentions” (such as /@([a-z][_a-z0-9])\b/gi) and want to create links to persons from them.

Install

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

npm install hast-util-find-and-replace

In Deno with esm.sh:

import {findAndReplace} from 'https://esm.sh/hast-util-find-and-replace@5'

In browsers with esm.sh:

<script type="module">
  import {findAndReplace} from 'https://esm.sh/hast-util-find-and-replace@5?bundle'
</script>

Use

import {h} from 'hastscript'
import {findAndReplace} from 'hast-util-find-and-replace'
import {inspect} from 'unist-util-inspect'

const tree = h('p', [
  'Some ',
  h('em', 'emphasis'),
  ', ',
  h('strong', 'importance'),
  ', and ',
  h('code', 'code'),
  '.'
])

findAndReplace(tree, [
  [/and/gi, 'or'],
  [/emphasis/gi, 'em'],
  [/importance/gi, 'strong'],
  [
    /code/gi,
    function ($0) {
      return h('a', {href: '//example.com#' + $0}, $0)
    }
  ]
])

console.log(inspect(tree))

Yields:

element<p>[9]
│ properties: {}
├─0 text "Some "
├─1 element<em>[1]
│   │ properties: {}
│   └─0 text "em"
├─2 text ", "
├─3 element<strong>[1]
│   │ properties: {}
│   └─0 text "strong"
├─4 text ", "
├─5 text "or"
├─6 text " "
├─7 element<code>[1]
│   │ properties: {}
│   └─0 element<a>[1]
│       │ properties: {"href":"//example.com#code"}
│       └─0 text "code"
└─8 text "."

API

This package exports the identifiers defaultIgnore and findAndReplace. There is no default export.

defaultIgnore

Default tag names to ignore (Array<string>).

The defaults are math, script, style, svg, and title.

findAndReplace(tree, list[, options])

Find patterns in a tree and replace them.

The algorithm searches the tree in preorder for complete values in Text nodes. Partial matches are not supported.

Parameters

• tree (Node) — tree to change
• list (FindAndReplaceList or FindAndReplaceTuple) — one or more find-and-replace pairs
• options (Options) — configuration

Returns

Nothing (undefined).

Find

Pattern to find (TypeScript type).

Strings are escaped and then turned into global expressions.

Type

type Find = RegExp | string

FindAndReplaceList

Several find and replaces, in array form (TypeScript type).

Type

type FindAndReplaceList = Array<FindAndReplaceTuple>

See FindAndReplaceTuple.

FindAndReplaceTuple

Find and replace in tuple form (TypeScript type).

Type

type FindAndReplaceTuple = [Find, Replace?]

See Find and Replace.

Options

Configuration (TypeScript type).

Fields

• ignore (Test, optional) — test for which elements to ignore

RegExpMatchObject

Info on the match (TypeScript type).

Fields

• index (number) — the index of the search at which the result was found
• input (string) — a copy of the search string in the text node
• stack (Array<Node>) — all ancestors of the text node, where the last node is the text itself

Replace

Thing to replace with (TypeScript type).

Type

type Replace = ReplaceFunction | string | null | undefined

See ReplaceFunction.

ReplaceFunction

Callback called when a search matches (TypeScript type).

Parameters

The parameters are the result of corresponding search expression:

• value (string) — whole match
• ...capture (Array<string>) — matches from regex capture groups
• match (RegExpMatchObject) — info on the match

Returns

Thing to replace with:

• when null, undefined, '', remove the match
• …or when false, do not replace at all
• …or when string, replace with a text node of that value
• …or when Array<Node> or Node, replace with those nodes

Types

This package is fully typed with TypeScript. It exports the additional types Find, FindAndReplaceList, FindAndReplaceTuple, Options, RegExpMatchObject, Replace, and ReplaceFunction.

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-find-and-replace@^5, compatible with Node.js 16.

Security

Use of hast-util-find-and-replace can open you up to a cross-site scripting (XSS) attack if a value used to replace is unsafe. Use hast-util-santize to make the hast tree safe.

The following example shows how a script is injected that runs when loaded in a browser.

const tree = h('p', 'This and that.')

findAndReplace(tree, 'and', function () {
  return h('script', 'alert(1)')
})

Yields:

<p>This <script>alert(1)</script> that.</p>

Related

• hast-util-select — querySelector, querySelectorAll, and matches
• mdast-util-find-and-replace — find and replace in mdast
• unist-util-select — select unist nodes with CSS-like selectors

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.

License

MIT © Titus Wormer