Registry / serialization / hast-util-from-html

hast-util-from-html

library2.0.3jsnpmunverified

hast-util-from-html is a utility within the unifiedjs ecosystem that transforms serialized HTML strings into a HAST (Hypertext Abstract Syntax Tree) representation. The current stable version is 2.0.3. It maintains a relatively active release cadence, with recent patch releases addressing type issues and a major version bump (2.0.0) introducing significant changes like ESM-only support and Node.js 16+ requirement. This package is designed for scenarios where developers need to manually manipulate HTML syntax trees, offering granular control over parsing. It differentiates itself from `parse5` (a low-level HTML parser) by directly producing HAST nodes, and from higher-level abstractions like `rehype-parse`. For browser environments, `hast-util-from-html-isomorphic` offers a lighter, albeit less feature-rich, alternative.

serialization web-framework

npm install hast-util-from-html

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · HAST-UTIL-FROM-HTM

hast-util-from-html

serializationjavascriptv2.0.3

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

fromHtml

✓ import { fromHtml } from 'hast-util-from-html'

✗ const { fromHtml } = require('hast-util-from-html')

Package is ESM-only since v2.0.0; Node.js 16+ is required. CommonJS `require` is not supported for direct imports.

ErrorCode

✓ import type { ErrorCode } from 'hast-util-from-html'

This is a TypeScript type, defining known parse error codes. For JavaScript users, it's not directly imported but describes values used in options.

Options

✓ import type { Options } from 'hast-util-from-html'

This is a TypeScript type, describing the configuration object for `fromHtml`. For JavaScript users, it's not directly imported but defines the shape of the `options` argument.

Demonstrates how to parse a simple HTML string into a HAST (Hypertext Abstract Syntax Tree) using the `fromHtml` function, showcasing both fragment and full document parsing.

import { fromHtml } from 'hast-util-from-html'; import type { Root } from 'hast'; const htmlInput = '<h1>Hello, <em>world</em>!</h1><p>This is a paragraph.</p>'; // Parse as a document fragment to avoid automatic <html>, <head>, <body> insertion. const tree: Root = fromHtml(htmlInput, { fragment: true }); console.log(JSON.stringify(tree, null, 2)); // Example of parsing as a full document const documentHtml = '<!DOCTYPE html><html><head><title>Test</title></head><body><h1>Doc</h1></body></html>'; const docTree: Root = fromHtml(documentHtml); console.log('\n--- Full Document Parse ---\n'); console.log(JSON.stringify(docTree, null, 2));

Debug

Known issues

breakingVersion 2.0.0 and above require Node.js 16 or higher. Using older Node.js versions will result in runtime errors.

fix

Upgrade your Node.js environment to version 16 or newer.

affects: >=2.0.0

breakingSince version 2.0.0, the package is ESM-only. CommonJS `require()` statements are no longer supported and will lead to `ERR_REQUIRE_ESM` errors.

fix

Migrate your codebase to use ES module `import` syntax (e.g., `import { fromHtml } from 'hast-util-from-html'`) and ensure your project is configured for ESM.

affects: >=2.0.0

breakingVersion 2.0.0 introduced the `exports` field in `package.json`. Direct imports of internal or non-public paths (e.g., `hast-util-from-html/lib/foo`) are no longer supported and will break.

fix

Only use the public API as exported from the main package entry point (`import { ... } from 'hast-util-from-html'`).

affects: >=2.0.0

gotchaBy default, `fromHtml` parses input as a complete HTML document, potentially inserting `<html>`, `<head>`, and `<body>` elements around your input. If you intend to parse only a snippet, use the `fragment: true` option.

fix

For parsing HTML fragments, use `fromHtml(value, { fragment: true })`.

affects: >=1.0.0

gotchaHTML parse errors are handled by an internal `parse5` parser. By default, these errors might be silently corrected or lead to unexpected tree structures. Configure the `onerror` option to control severity or provide a custom handler.

fix

Review the API documentation for `OnError`, `ErrorCode`, and `ErrorSeverity` to customize how parse errors are reported or handled via the `onerror` option.

affects: >=1.0.0

Errors

Common errors & fixes

ERR_REQUIRE_ESM

Attempting to `require()` `hast-util-from-html` in a CommonJS environment, which is an ESM-only package since v2.0.0.

fix

Switch to ES module `import` syntax: `import { fromHtml } from 'hast-util-from-html'` and ensure your project is configured to run ESM.

SyntaxError: Named export 'fromHtml' not found. The requested module 'hast-util-from-html' does not provide an export named 'fromHtml'

This error can occur in environments where a CommonJS `require` call is used, or when incorrectly trying to import named exports from an ESM module in some configurations.

fix

Verify that your project is using `import { fromHtml } from 'hast-util-from-html'` and that your environment (Node.js version, bundler config) supports ESM correctly.

TypeError: fromHtml is not a function

This often happens if you try to `require` the package and destructure an non-existent default export, or if your import statement is incorrect (e.g., trying to import a default when it's a named export).

fix

For ESM, ensure you use `import { fromHtml } from 'hast-util-from-html'`. If you are using an older version (pre-v2) with CommonJS, ensure you're accessing the correct export property if it wasn't the default.

Upgrade

Version history

2.0.3latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/syntax-tree/hast-util-from-html ↗

packagehttps://www.npmjs.com/package/hast-util-from-html ↗

homepagehttps://unifiedjs.com ↗