hast-util-minify-whitespace: HTML Whitespace Minification

1.0.1 · active · verified Sun Apr 19

hast-util-minify-whitespace is a focused utility within the unified ecosystem, specifically designed to optimize HTML by minifying whitespace between elements in a `hast` (HTML Abstract Syntax Tree). It reduces multiple consecutive whitespace characters to a single space, or to a newline if configured, thereby improving the size of HTML fragments. The package is currently at version 1.0.1, with releases coordinated within the larger `rehypejs` collective, which emphasizes modern JavaScript practices. Key differentiators include its robust integration into the pluggable unified processing pipeline, full TypeScript support, and its commitment to WHATWG HTML parsing standards. It operates as an ESM-only module and requires Node.js 16 or newer, aligning with contemporary Node.js environments.

Common errors

```
ERR_REQUIRE_ESM: require() of ES Module ... not supported.
```
cause Attempting to use `require()` to import an ESM-only package.

fix Change `const minifyWhitespace = require('hast-util-minify-whitespace')` to `import { minifyWhitespace } from 'hast-util-minify-whitespace'` and ensure your project is configured for ESM.
```
minifyWhitespace is not a function
```
cause Trying to access `minifyWhitespace` as a property of the module object when using `require()` on an ESM-only package, or incorrectly destructuring named exports.

fix Confirm you are using `import { minifyWhitespace } from 'hast-util-minify-whitespace'` and that your environment supports ESM.
```
ReferenceError: h is not defined
```
cause The `h` function from `hastscript` was used in an example or your code without being installed or imported.

fix Install `hastscript` (`npm install hastscript`) and ensure you `import { h } from 'hastscript'` in your file.

Warnings

breaking This package, like all packages in the `rehypejs` monorepo, now requires Node.js 16 or newer. Older Node.js versions are no longer supported.
Fix: Upgrade your Node.js environment to version 16 or later.
breaking This package is ESM-only. Attempting to import it using CommonJS `require()` will result in errors.
Fix: Ensure your project uses ES modules (`import`) and configure your `package.json` with `"type": "module"` or use `.mjs` extensions for files importing this package.
breaking The `rehypejs` monorepo, which this package is part of, now uses the `exports` field in `package.json`. This may affect how bundlers and older Node.js versions resolve imports.
Fix: Ensure your build tooling and Node.js environment are up to date and correctly configured to handle the `exports` field. Avoid relying on undocumented subpath imports.
gotcha Minifying whitespace within a `hast` tree does not inherently protect against Cross-Site Scripting (XSS) vulnerabilities. If the processed HTML is rendered without further sanitization, it could still be unsafe.
Fix: Always use `rehype-sanitize` or a similar sanitization utility on your `hast` tree before serializing it to HTML, especially if the input HTML is untrusted.

Install

npm install hast-util-minify-whitespace npm
yarn add hast-util-minify-whitespace yarn
pnpm add hast-util-minify-whitespace pnpm

Imports

minifyWhitespace

wrong:

const minifyWhitespace = require('hast-util-minify-whitespace')

correct:

import { minifyWhitespace } from 'hast-util-minify-whitespace'

This package is ESM-only since v1.0.0; CommonJS `require()` is not supported.

h
wrong:
```
const h = require('hastscript')
```
correct:
```
import { h } from 'hastscript'
```
While not part of this package, `hastscript` is commonly used to create `hast` nodes and is often a companion dependency for testing or examples.
Options
```
import type { Options } from 'hast-util-minify-whitespace'
```
Import the TypeScript type definition for configuration options.

Quickstart

Demonstrates how to import and use `minifyWhitespace` to process a `hast` tree created with `hastscript`, showing the transformation of internal whitespace.

import { h } from 'hastscript';
import { minifyWhitespace } from 'hast-util-minify-whitespace';

const tree = h('p', [
  '  ',
  h('strong', 'foo'),
  '  ',
  h('em', 'bar'),
  '  ',
  h('meta', { itemProp: true }),
  '  '
]);

console.log('Original tree:\n', JSON.stringify(tree, null, 2));

minifyWhitespace(tree);

console.log('\nMinified tree:\n', JSON.stringify(tree, null, 2));

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