hast-util-to-xast

3.0.1 verified Sat May 09 auth: no javascript

Utility to transform a hast (HTML) syntax tree into a xast (XML) syntax tree. v3.0.1, ESM-only, fully typed with TypeScript. Supports automatic SVG namespace switching and embedded MDX nodes. Commonly used for EPUB generation. Requires Node.js 16+. Replaced old direct `space` argument with `options.space` in v3.

Common errors

error TypeError: toXast is not a function ↓

cause Using default import instead of named import (e.g., `import toXast from 'hast-util-to-xast'`). Package only exports named export.

fix

Change import to import { toXast } from 'hast-util-to-xast'.

error Error [ERR_REQUIRE_ESM]: require() of ES Module /path/to/hast-util-to-xast/index.js from /path/to/project/index.js not supported. ↓

cause Using require() on an ESM-only package.

fix

Use import() or switch to ESM in your project (package.json type: module).

error TypeError: The "original" argument must be of type function. Received an instance of Object ↓

cause Passing a string as second argument instead of an options object in v3+.

fix

Change toXast(hast, 'svg') to toXast(hast, { space: 'svg' }).

Warnings

breaking Removed direct `space` string argument; use `options.space` instead. ↓

fix Pass `{ space: 'svg' }` instead of `'svg'` as second argument.

breaking Changed to ESM-only. No CommonJS support starting from v3. ↓

fix Use `import { toXast } from 'hast-util-to-xast'` or dynamic `import()`.

breaking Dropped support for Node.js < 16. ↓

fix Upgrade Node.js to version 16 or later.

gotcha When space is 'html', SVG elements are automatically detected and switched to SVG namespace, but custom XML namespaces not supported. ↓

fix Use explicit `xmlns` attributes for non-SVG custom namespaces (may not be preserved).

Install

npm install hast-util-to-xast

yarn add hast-util-to-xast

pnpm add hast-util-to-xast

Imports

toXast
wrong
```
import toXast from 'hast-util-to-xast'
```
correct
```
import { toXast } from 'hast-util-to-xast'
```
This package has no default export; use named import only. Also works with `const { toXast } = await import('hast-util-to-xast')`.
Options
wrong
```
import { Options } from 'hast-util-to-xast'
```
correct
```
import type { Options } from 'hast-util-to-xast'
```
Options is a TypeScript type, not a runtime value. Use `import type` to avoid runtime inclusion.

Space

wrong

import { Space } from 'hast-util-to-xast'

correct

import type { Space } from 'hast-util-to-xast'

Space is a TypeScript type, not a runtime value. Use `import type`.

Quickstart

Parses HTML with hast-util-from-html, converts to xast, then serializes to XML string.

import { fromHtml } from 'hast-util-from-html'
import { toXast } from 'hast-util-to-xast'
import { toXml } from 'xast-util-to-xml'

const html = `<!DOCTYPE html><title>Hello</title><h1>World</h1>`
const hast = fromHtml(html)
const xast = toXast(hast, { space: 'html' })
const xml = toXml(xast)
console.log(xml)
// <?xml version="1.0" encoding="utf-8"?><!DOCTYPE html><html xmlns="http://www.w3.org/1999/xhtml"><head><title>Hello</title></head><body><h1>World</h1></body></html>