W3C HTML Validator

https://www.npmjs.com/package/w3c-html-validator
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W3C HTML Validator checks the markup validity of HTML files using the W3C validator and produces...
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### Examples

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=readme

Practical examples demonstrating the usage of the CLI with various flags.

```APIDOC
## Examples

* `html-validator`
  Validates all HTML files in the project.
* `html-validator docs --exclude=build,tmp`
  Validates all HTML files in the **docs** folder except files which have "build" or "tmp" anywhere in their pathname or filename.
* `html-validator docs '--ignore=Trailing slash on void elements'`
  Allows the ugly slashes of self-closing tags despite XHTML being a hideous scourge on the web.
* `html-validator docs '--ignore=/^Duplicate ID/'`
  Uses a regex (regular expression) to skip all HTML validation messages that start with "Duplicate ID".
* `html-validator docs '--ignore=/^Duplicate ID|^Section lacks|^Element .blockquote. not allowed/'`
  Uses a regex with "or" operators (`|`) to skip multiple HTML validation messages.
* `html-validator docs --ignore-config=spec/ignore-config.txt`
  Similar to the pervious command but strings and regexes are stored in a configuration file (see the _Configuration File for Ignore Patterns_ section below).
* `html-validator --default-rules --quiet`
  Skip all HTML validation messages in the built-in opinionated ignore list and also suppresses all the "pass" status messages.
* `html-validator docs --delay=200`
  Validates all HTML files in the **docs** folder at a rate of 1 file per 200 ms (default is 500 ms).
* `html-validator docs --trim=30 --continue`
  Truncates validation messages to 30 characters and does not abort CI if validation fails.
* `html-validator docs --check-url=http://localhost/nu/ --delay=0`
  Uses a locally hosted W3C validator, such as the docker-validator-w3c server.

> [!NOTE] _Single quotes in commands are normalized so they work cross-platform and avoid the errors often encountered on Microsoft Windows._
```

--------------------------------

### Ignore Configuration File Example

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Example content for an ignore configuration file, where each line specifies a string or regex for messages to be skipped. Lines starting with '#' are comments.

```text
# Example configuration file with 3 regexes:

```

--------------------------------

### Run Example Validation

Source: https://www.npmjs.com/package/w3c-html-validator

Commands to execute the provided example script.

```bash
$ cd w3c-html-validator
$ node examples.js
```

--------------------------------

### Installation

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Install the w3c-html-validator package as a development dependency.

```APIDOC
## Installation

Install package for node:
```bash
$ npm install --save-dev w3c-html-validator
```
```

--------------------------------

### Examples

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Practical examples demonstrating various ways to use the html-validator CLI.

```APIDOC
## Examples

* `html-validator`
Validates all HTML files in the project.

* `html-validator docs --exclude=build,tmp`
Validates all HTML files in the **docs** folder except files which have "build" or "tmp" anywhere in their pathname or filename.

* `html-validator docs '--ignore=Trailing slash on void elements'`
Allows the ugly slashes of self-closing tags despite XHTML being a hideous scourge on the web.

* `html-validator docs '--ignore=/^Duplicate ID/'`
Uses a regex (regular expression) to skip all HTML validation messages that start with "Duplicate ID".

* `html-validator docs '--ignore=/^Duplicate ID|^Section lacks|^Element .blockquote. not allowed/'`
Uses a regex with "or" operators (`|`) to skip multiple HTML validation messages.

* `html-validator docs --ignore-config=spec/ignore-config.txt`
Similar to the pervious command but strings and regexes are stored in a configuration file (see the _Configuration File for Ignore Patterns_ section below).

* `html-validator --default-rules --quiet`
Skip all HTML validation messages in the built-in opinionated ignore list and also suppresses all the "pass" status messages.

* `html-validator docs --delay=200`
Validates all HTML files in the **docs** folder at a rate of 1 file per 200 ms (default is 500 ms).

* `html-validator docs --trim=30 --continue`
Truncates validation messages to 30 characters and does not abort CI if validation fails.

* `html-validator docs --check-url=http://localhost/nu/ --delay=0`
Uses a locally hosted W3C validator, such as the docker-validator-w3c server.

> [!NOTE] _Single quotes in commands are normalized so they work cross-platform and avoid the errors often encountered on Microsoft Windows._
```

--------------------------------

### Examples

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=dependencies

Practical examples demonstrating various ways to use the html-validator command with different flags and parameters.

```APIDOC
### 5. Examples

* `html-validator`
Validates all HTML files in the project.
* `html-validator docs --exclude=build,tmp`
Validates all HTML files in the **docs** folder except files which have "build" or "tmp" anywhere in their pathname or filename.
* `html-validator docs '--ignore=Trailing slash on void elements'`
Allows the ugly slashes of self-closing tags despite XHTML being a hideous scourge on the web.
* `html-validator docs '--ignore=/^Duplicate ID/'`
Uses a regex (regular expression) to skip all HTML validation messages that start with "Duplicate ID".
* `html-validator docs '--ignore=/^Duplicate ID|^Section lacks|^Element .blockquote. not allowed/'`
Uses a regex with "or" operators (`|`) to skip multiple HTML validation messages.
* `html-validator docs --ignore-config=spec/ignore-config.txt`
Similar to the pervious command but strings and regexes are stored in a configuration file (see the _Configuration File for Ignore Patterns_ section below).
* `html-validator --default-rules --quiet`
Skip all HTML validation messages in the built-in opinionated ignore list and also suppresses all the "pass" status messages.
* `html-validator docs --delay=200`
Validates all HTML files in the **docs** folder at a rate of 1 file per 200 ms (default is 500 ms).
* `html-validator docs --trim=30 --continue`
Truncates validation messages to 30 characters and does not abort CI if validation fails.
* `html-validator docs --check-url=http://localhost/nu/ --delay=0`
Uses a locally hosted W3C validator, such as the docker-validator-w3c server.

> [!NOTE] _Single quotes in commands are normalized so they work cross-platform and avoid the errors often encountered on Microsoft Windows._
```

--------------------------------

### Install w3c-html-validator

Source: https://www.npmjs.com/package/w3c-html-validator

Install the package as a development dependency in your Node.js project.

```bash
$ npm install --save-dev w3c-html-validator
```

--------------------------------

### Mocha Example for w3c-html-validator

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=dependencies

This example demonstrates how to use the w3c-html-validator in a Mocha test to validate an HTML file. Ensure the 'w3c-html-validator' and 'assert' modules are installed.

```javascript
import assert from 'assert';
import { w3cHtmlValidator } from 'w3c-html-validator';

describe('Home page', () => {

   it('validates', (done) => {
      const handleResults = (results) => {
         assert(results.status === 200, 'Request succeeded');
         assert(results.validates,      'Home page validates');
         done();
         };
      const options = { filename: 'docs/index.html' };
      w3cHtmlValidator.validate(options).then(handleResults);
      });

   });

```

--------------------------------

### Install w3c-html-validator

Source: https://www.npmjs.com/package/w3c-html-validator

Install the package via npm to access the validator functionality.

```bash
npm i w3c-html-validator
```

--------------------------------

### Command-line Execution with npx

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=readme

Execute the validator using npx for direct command-line use after installation.

```APIDOC
## Command-line Execution with npx

Example terminal commands:
```bash
$ npm install --save-dev w3c-html-validator
$ npx html-validator docs
```

The above `npx` line validates all the HTML files in the **docs** folder. You can also install **w3c-html-validator** globally (`--global`) and then run it anywhere directly from the terminal.
```

--------------------------------

### Run Validator via npx

Source: https://www.npmjs.com/package/w3c-html-validator

Execute the validator directly using npx without global installation.

```bash
$ npm install --save-dev w3c-html-validator
$ npx html-validator docs
```

--------------------------------

### Usage - Command Line Interface

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=dependencies

Learn how to use the html-validator command-line tool, including basic usage, package.json scripts, and npx.

```APIDOC
## Usage

### 1. Synopsis

```bash
html-validator [INPUT1] [INPUT2] [INPUT3] [...]
```

Parameters: Each parameter is a folder or file to be sent to the HTML validator.

### 2. npm package.json scripts

Run `html-validator` from the `"scripts"` section of your **package.json** file.

Example **package.json** scripts:

```json
   "scripts": {
      "validate":   "html-validator docs flyer.html",
      "one-folder": "html-validator docs",
      "all":        "html-validator --quiet"
   },
```

Passing no parameters defaults to validating all HTML files in the project (skipping the **node_modules** folder).

### 3. Command-line npx

Example terminal commands:

```bash
$ npm install --save-dev w3c-html-validator
$ npx html-validator docs
```

The above `npx` line validates all the HTML files in the **docs** folder.

You can also install **w3c-html-validator** globally (`--global`) and then run it anywhere directly from the terminal.
```

--------------------------------

### Import and Validate HTML

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=versions

Demonstrates how to import the validator and use the `validate` function with options. It also shows how to use the `reporter` for formatted output.

```APIDOC
## Import and Validate HTML

### Description
This section shows how to import the `w3cHtmlValidator` and use its `validate` function. You can provide options such as `filename` to specify the HTML file to validate. The results can be logged directly or formatted using the `reporter` function.

### Method
`import { w3cHtmlValidator } from 'w3c-html-validator';`

### Endpoint
N/A (Programmatic Usage)

### Parameters
#### Request Body (for `validate` function)
- **options** (object) - Required - Configuration options for validation.
  - **filename** (string) - Optional - HTML file to validate.
  - **html** (string) - Optional - HTML string to validate.
  - **checkUrl** (string) - Optional - W3C validation API endpoint. Defaults to 'https://validator.w3.org/nu/'.
  - **defaultRules** (boolean) - Optional - Apply additional built-in opinionated ignore list. Defaults to `false`.
  - **dryRun** (boolean) - Optional - Bypass validation. Defaults to `false`.
  - **ignoreLevel** (string) - Optional - Skip unwanted messages. Can be `'info'` or `'warning'`. Defaults to `null`.
  - **ignoreMessages** (array) - Optional - Skip messages containing a string or matching a regex. Defaults to `[]`.
  - **output** (string) - Optional - Get results as `'json'` or `'html'`. Defaults to `'json'`.
  - **website** (string) - Optional - URL of website to validate.

#### Parameters for `reporter` function
- **results** (object) - Required - The results object returned by `validate`.
- **options** (object) - Optional - Configuration options for the reporter.
  - **continueOnFail** (boolean) - Optional - Report messages but do not throw an error if validation failed. Defaults to `false`.
  - **maxMessageLen** (number) - Optional - Trim validation messages to not exceed a maximum length. Defaults to `null`.
  - **quiet** (boolean) - Optional - Suppress status messages for successful validations. Defaults to `false`.
  - **title** (string) - Optional - Override display title. Defaults to `null`.

### Request Example
```javascript
import { w3cHtmlValidator } from 'w3c-html-validator';

const options = { filename: 'docs/index.html' };
w3cHtmlValidator.validate(options).then(console.log); // outputs the results object

// To display formatted output:
w3cHtmlValidator.validate(options).then(w3cHtmlValidator.reporter);
```

### Response
#### Success Response (Promise resolving to ValidatorResults)
- **validates** (boolean) - Indicates if the HTML is valid.
- **mode** (string) - The validation mode used ('html', 'filename', or 'website').
- **html** (string | null) - The validated HTML content if mode is 'html'.
- **filename** (string | null) - The validated filename if mode is 'filename'.
- **website** (string | null) - The validated website URL if mode is 'website'.
- **output** (string) - The format of the output ('json' or 'html').
- **status** (number) - The HTTP status code of the validation response.
- **messages** (array | null) - An array of validation messages if output is 'json'.
- **display** (string | null) - The formatted HTML output if output is 'html'.
- **dryRun** (boolean) - Indicates if the validation was a dry run.
```

--------------------------------

### Import and Validate HTML

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Demonstrates how to import the validator and use the `validate` function with options. It also shows how to use the `reporter` for formatted output.

```APIDOC
## Import and Validate HTML

### Description
This section shows how to import the `w3cHtmlValidator` and use its `validate` function. You can provide options such as `filename` to specify the HTML file to validate. The results can be logged directly or formatted using the `reporter` function.

### Method
`import { w3cHtmlValidator } from 'w3c-html-validator';`

### Endpoint
N/A (Programmatic Usage)

### Parameters
#### Request Body (for `validate` function)
- **options** (object) - Required - Configuration options for validation.
  - **filename** (string) - Optional - Path to the HTML file to validate.
  - **html** (string) - Optional - HTML string to validate.
  - **checkUrl** (string) - Optional - W3C validation API endpoint. Defaults to 'https://validator.w3.org/nu/'.
  - **defaultRules** (boolean) - Optional - Apply an additional built-in ignore list. Defaults to `false`.
  - **dryRun** (boolean) - Optional - Bypass validation. Defaults to `false`.
  - **ignoreLevel** (string) - Optional - Skip messages with a specific level ('info' or 'warning'). Only works for 'json' output. Defaults to `null`.
  - **ignoreMessages** (array) - Optional - Skip messages containing a string or matching a regex. Only works for 'json' output. Defaults to `[]`.
  - **output** (string) - Optional - Format of the results ('json' or 'html'). Defaults to 'json'.
  - **website** (string) - Optional - URL of the website to validate.

#### Parameters for `reporter` function
- **results** (object) - Required - The validation results object returned by `validate()`.
- **options** (object) - Optional - Configuration options for the reporter.
  - **continueOnFail** (boolean) - Optional - Report messages but do not throw an error if validation failed. Defaults to `false`.
  - **maxMessageLen** (number) - Optional - Trim validation messages to not exceed a maximum length. Defaults to `null`.
  - **quiet** (boolean) - Optional - Suppress status messages for successful validations. Defaults to `false`.
  - **title** (string) - Optional - Override display title. Defaults to `null`.

### Request Example
```javascript
import { w3cHtmlValidator } from 'w3c-html-validator';

const options = { filename: 'docs/index.html' };
w3cHtmlValidator.validate(options).then(console.log); // outputs the results object

// To display formatted output:
w3cHtmlValidator.validate(options).then(w3cHtmlValidator.reporter);
```

### Response
#### Success Response (Promise resolves with ValidatorResults object)
- **validates** (boolean) - Indicates if the HTML is valid.
- **mode** (string) - The validation mode ('html', 'filename', or 'website').
- **html** (string | null) - The validated HTML content if mode is 'html'.
- **filename** (string | null) - The validated filename if mode is 'filename'.
- **website** (string | null) - The validated website URL if mode is 'website'.
- **output** (string) - The format of the output ('json' or 'html').
- **status** (number) - The HTTP status code of the validation response.
- **messages** (array | null) - An array of validation messages if output is 'json'.
- **display** (string | null) - The formatted HTML output if output is 'html'.
- **dryRun** (boolean) - Indicates if the validation was a dry run.

#### Response Example (for `console.log`)
```json
{
  "validates": true,
  "mode": "filename",
  "html": null,
  "filename": "docs/index.html",
  "website": null,
  "output": "json",
  "status": 200,
  "messages": [],
  "display": null,
  "dryRun": false
}
```
```

--------------------------------

### HTML Validator Synopsis

Source: https://www.npmjs.com/package/w3c-html-validator

General syntax for running the validator from the command line.

```bash
html-validator [INPUT1] [INPUT2] [INPUT3] [...]
```

--------------------------------

### CLI Usage and Flags

Source: https://www.npmjs.com/package/w3c-html-validator

Details on how to use the html-validator command-line tool and the available configuration flags.

```APIDOC
## CLI Command: html-validator

### Description
Validates HTML files or folders using the W3C validator. If no parameters are provided, it defaults to validating all HTML files in the project (excluding node_modules).

### Usage
`html-validator [INPUT1] [INPUT2] [...] [FLAGS]`

### Parameters
#### Path Parameters
- **INPUT** (string) - Optional - A folder or file path to be sent to the HTML validator.

### CLI Flags
- **--check-url** (string) - Optional - W3C validation API endpoint (e.g., http://localhost/nu/).
- **--continue** (boolean) - Optional - Report messages but do not throw an error if validation failed.
- **--default-rules** (boolean) - Optional - Apply additional built-in opinionated ignore list.
- **--delay** (number) - Optional - Debounce pause in milliseconds between each file validation.
- **--dry-run** (boolean) - Optional - Bypass validation.
- **--exclude** (string) - Optional - Comma separated list of strings to match in paths to skip.
- **--ignore-config** (string) - Optional - File containing strings and regexes of validation messages to skip.
- **--ignore** (string) - Optional - Skip validation messages containing a string or matching a regex.
- **--note** (string) - Optional - Comment for human reference.
- **--quiet** (boolean) - Optional - Suppress messages for successful validations.
- **--trim** (number) - Optional - Truncate validation messages to a maximum length.
```

--------------------------------

### Import and Validate HTML

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=readme

Demonstrates how to import the w3cHtmlValidator and use the validate function with options to check an HTML file. It shows how to log the raw results or use a formatted reporter.

```APIDOC
## Import and Validate HTML

### Description
This section shows how to import the `w3cHtmlValidator` module and use its `validate` function to check an HTML file. It includes examples for logging raw results and using the `reporter` for formatted output.

### Method
`w3cHtmlValidator.validate(options)`

### Parameters
#### Request Body
- **options** (object) - Required - Configuration options for validation.
  - **filename** (string) - Optional - Path to the HTML file to validate.
  - **html** (string) - Optional - HTML string to validate.
  - **website** (string) - Optional - URL of the website to validate.
  - **checkUrl** (string) - Optional - Defaults to 'https://validator.w3.org/nu/'. The W3C validation API endpoint.
  - **defaultRules** (boolean) - Optional - Defaults to `false`. Apply an additional built-in ignore list.
  - **dryRun** (boolean) - Optional - Defaults to `false`. Bypass validation.
  - **ignoreLevel** (string) - Optional - `'info'` or `'warning'`. Skip messages with this level or lower. Only works for JSON output.
  - **ignoreMessages** (array) - Optional - Array of strings or regex patterns to ignore in validation messages. Only works for JSON output.
  - **output** (string) - Optional - Defaults to `'json'`. `'json'` for results array, `'html'` for web page output.

### Request Example
```javascript
import { w3cHtmlValidator } from 'w3c-html-validator';

const options = { filename: 'docs/index.html' };
w3cHtmlValidator.validate(options).then(console.log); // Outputs the results object

w3cHtmlValidator.validate(options).then(w3cHtmlValidator.reporter); // Outputs formatted results
```

### Response
#### Success Response (Promise resolves with ValidatorResults object)
- **validates** (boolean) - Indicates if the HTML is valid.
- **mode** (string) - The validation mode used ('html', 'filename', 'website').
- **html** (string | null) - The validated HTML content if mode is 'html'.
- **filename** (string | null) - The validated filename if mode is 'filename'.
- **website** (string | null) - The validated website URL if mode is 'website'.
- **output** (string) - The format of the output ('json' or 'html').
- **status** (number) - The HTTP status code of the validation response.
- **messages** (array | null) - An array of validation messages if output is 'json'.
- **display** (string | null) - Formatted output string if output is 'html'.
- **dryRun** (boolean) - Indicates if the validation was a dry run.
```

--------------------------------

### Basic Usage

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Validate HTML files or folders using the command-line interface.

```APIDOC
## Basic Usage

### Synopsis
```bash
html-validator [INPUT1] [INPUT2] [INPUT3] [...]
```

Parameters: Each parameter is a folder or file to be sent to the HTML validator.

### npm package.json scripts
Run `html-validator` from the `"scripts"` section of your **package.json** file.

Example **package.json** scripts:
```json
   "scripts": {
      "validate":   "html-validator docs flyer.html",
      "one-folder": "html-validator docs",
      "all":        "html-validator --quiet"
   },
```

Passing no parameters defaults to validating all HTML files in the project (skipping the **node_modules** folder).

### Command-line npx
Example terminal commands:
```bash
$ npm install --save-dev w3c-html-validator
$ npx html-validator docs
```

The above `npx` line validates all the HTML files in the **docs** folder.
You can also install **w3c-html-validator** globally (`--global`) and then run it anywhere directly from the terminal.
```

--------------------------------

### Basic Usage

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=readme

Validate HTML files by providing them as arguments or by using npm scripts.

```APIDOC
## Basic Usage

### 1. Synopsis

Validate HTML files by listing them as arguments:
```bash
html-validator [INPUT1] [INPUT2] [INPUT3] [...]
```

Parameters: Each parameter is a folder or file to be sent to the HTML validator.

### 2. npm package.json scripts

Run `html-validator` from the `"scripts"` section of your **package.json** file.

Example **package.json** scripts:
```json
   "scripts": {
      "validate":   "html-validator docs flyer.html",
      "one-folder": "html-validator docs",
      "all":        "html-validator --quiet"
   }
```

Passing no parameters defaults to validating all HTML files in the project (skipping the **node_modules** folder).
```

--------------------------------

### Configure package.json Scripts

Source: https://www.npmjs.com/package/w3c-html-validator

Define validation commands within the scripts section of your package.json file.

```json
   "scripts": {
      "validate":   "html-validator docs flyer.html",
      "one-folder": "html-validator docs",
      "all":        "html-validator --quiet"
   },
```

--------------------------------

### Configuration File for Ignore Patterns

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Details on how to use a configuration file to specify patterns for ignoring validation messages.

```APIDOC
## Configuration File for Ignore Patterns

The optional `--ignore-config=FILENAME` flag specifies a configuration file with one string or regex per line. HTML validation messages containing any of the strings or matching any of the regexes will be skipped. Empty lines and lines starting with a hash sign (`#`) are treated as comments and do nothing.

Example configuration file with 3 regexes:
```
```

--------------------------------

### Apply Default Rules and Quiet Mode

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Use --default-rules to apply an opinionated ignore list and --quiet to suppress success messages.

```bash
html-validator --default-rules --quiet
```

--------------------------------

### Ignore Configuration

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Details on how to configure message ignoring using regex patterns and the default ignore list.

```APIDOC
## Ignore Configuration

### Description
This section explains how to configure the validator to ignore specific validation messages using regular expressions or a default list of common, often unhelpful, messages.

### Method
Configuration is done via the `ignoreMessages` and `ignoreLevel` options when calling `w3cHtmlValidator.validate()`.

### Parameters
#### `ignoreMessages` (array)
- Type: `array`
- Default: `[]`
- Description: An array of strings or regular expressions. Messages containing a string or matching a regex in this list will be ignored. This option only works for `'json'` output.

#### `ignoreLevel` (string)
- Type: `'info'` or `'warning'`
- Default: `null`
- Description: Skips messages with a level equal to or less than the specified level. Setting `ignoreLevel` to `'warning'` skips both `'warning'` and `'info'` level messages. This option only works for `'json'` output.

### Default Ignore List
The `--default-rules` flag (or `defaultRules: true` option) applies an opinionated pre-defined list of messages that are often considered unhelpful.

| Pattern                | Level   | Explanation                                                                                                |
|------------------------|---------|------------------------------------------------------------------------------------------------------------|
| `with computed level`  | error   | Ridiculous that adding an `<aside>` with an `<h2>` breaks the outer flow's outline.                         |
| `Section lacks heading.` | warning | Rule is sensible for traditional print publishing but absurd for modern UI components not burning in nested `<div>` hell. |

### Request Example (using options)
```javascript
import { w3cHtmlValidator } from 'w3c-html-validator';

const options = {
  filename: 'index.html',
  output: 'json',
  ignoreLevel: 'warning',
  ignoreMessages: [
    /^Duplicate ID/,
    /^Element .blockquote. not allowed/,
    /^Element .style. not allowed/
  ]
};

w3cHtmlValidator.validate(options).then(console.log);
```

### Response Example (showing ignored messages)
If messages matching the ignore criteria are found, they will not be present in the `messages` array of the results object when `output` is 'json'.
```

--------------------------------

### Ignore Messages Using a Configuration File

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Specify a file path with the --ignore-config flag, where each line contains a string or regex for messages to be skipped.

```bash
html-validator docs --ignore-config=spec/ignore-config.txt
```

--------------------------------

### Validate All HTML Files

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Run the validator without any specific file or folder arguments to validate all HTML files in the project, excluding node_modules.

```bash
html-validator
```

--------------------------------

### Ignore Configuration

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=dependencies

Explains how to configure ignore patterns for validation messages using regular expressions.

```APIDOC
## Ignore Config for w3c-html-validator

### Description
This section details how to configure ignore patterns for validation messages. You can specify regular expressions to skip certain messages during validation.

### Method
N/A (Configuration via Regex Patterns)

### Endpoint
N/A (Configuration within code)

### Parameters
#### Ignore Patterns (Regex)
- **`/^Duplicate ID/`**: Ignores messages starting with 'Duplicate ID'.
- **`/^Element .blockquote. not allowed/`**: Ignores messages about disallowed blockquote elements.
- **`/^Element .style. not allowed/`**: Ignores messages about disallowed style elements.

### Explanation
The caret (`^`) regex operator matches the beginning of the validation message. The dot (`.`) regex operator matches any single character, useful for handling variations like different quote types.
```

--------------------------------

### Use Local W3C Validator

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Point the validator to a custom W3C validation API endpoint, such as a locally hosted Docker instance, using the --check-url flag.

```bash
html-validator docs --check-url=http://localhost/nu/ --delay=0
```

--------------------------------

### CLI Flags

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=dependencies

A comprehensive list of command-line flags available for the w3c-html-validator tool, with descriptions and value types.

```APIDOC
### 4. CLI flags

Command-line flags:

Flag | Description | Value
---|---|---
`--check-url` | W3C validation API endpoint (example: `http://localhost/nu/`). | **string**
`--continue` | Report messages but do not throw an error if validation failed. | N/A
`--default-rules` | Apply additional built-in opinionated ignore list. | N/A
`--delay` | Debounce pause in milliseconds between each file validation. | **number**
`--dry-run` | Bypass validation (for usage while building your CI). | N/A
`--exclude` | Comma separated list of strings to match in paths to skip. | **string**
`--ignore-config` | File containing strings and regexes of validation messages to skip. | **string**
`--ignore` | Skip validation messages containing a string or matching a regex. | **string**
`--note` | Place to add a comment only for humans. | **string**
`--quiet` | Suppress messages for successful validations. | N/A
`--trim` | Truncate validation messages to not exceed a maximum length. | **number**
```

--------------------------------

### CLI Flags

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Available command-line flags to customize the validation process.

```APIDOC
## CLI Flags

Command-line flags:

Flag | Description | Value
---|---|---
`--check-url` | W3C validation API endpoint (example: `http://localhost/nu/`). | **string**
`--continue` | Report messages but do not throw an error if validation failed. | N/A
`--default-rules` | Apply additional built-in opinionated ignore list. | N/A
`--delay` | Debounce pause in milliseconds between each file validation. | **number**
`--dry-run` | Bypass validation (for usage while building your CI). | N/A
`--exclude` | Comma separated list of strings to match in paths to skip. | **string**
`--ignore-config` | File containing strings and regexes of validation messages to skip. | **string**
`--ignore` | Skip validation messages containing a string or matching a regex. | **string**
`--note` | Place to add a comment only for humans. | **string**
`--quiet` | Suppress messages for successful validations. | N/A
`--trim` | Truncate validation messages to not exceed a maximum length. | **number**
```

--------------------------------

### w3cHtmlValidator.reporter Options

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=dependencies

Details the options available for the `reporter` function, which formats the validation results.

```APIDOC
## w3cHtmlValidator.reporter(results, options)

### Description
The `reporter` function formats the validation results for display. It accepts the validation results and an optional options object to customize the output.

### Method
`w3cHtmlValidator.reporter(results, options)`

### Endpoint
N/A (Programmatic Usage)

### Parameters
#### Request Body
- **results** (object) - Required - The results object returned by `w3cHtmlValidator.validate()`.
- **options** (object) - Optional - Configuration options for the reporter.
  - **continueOnFail** (boolean) - Optional - Report messages but do not throw an error if validation failed. Defaults to `false`.
  - **maxMessageLen** (number) - Optional - Trim validation messages to not exceed a maximum length.
  - **quiet** (boolean) - Optional - Suppress status messages for successful validations. Defaults to `false`.
  - **title** (string) - Optional - Override the display title (useful for naming HTML string inputs).
```

--------------------------------

### Trim Messages and Continue on Failure

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Shorten validation messages to a specified length with --trim and prevent CI from aborting on validation failures with --continue.

```bash
html-validator docs --trim=30 --continue
```

--------------------------------

### Validate HTML Programmatically

Source: https://www.npmjs.com/package/w3c-html-validator

Import the validator and execute a validation check on a file.

```javascript
import { w3cHtmlValidator } from 'w3c-html-validator';

const options = { filename: 'docs/index.html' };
w3cHtmlValidator.validate(options).then(console.log);  //outputs the resutls object
```

--------------------------------

### Reporter Options

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=readme

Details the options available for the `w3cHtmlValidator.reporter` function, which formats and displays validation results.

```APIDOC
## Reporter Options

### Description
This section describes the options that can be passed to the `w3cHtmlValidator.reporter` function to customize how validation results are displayed.

### Method
`w3cHtmlValidator.reporter(results, options)`

### Parameters
#### Request Body
- **results** (object) - Required - The results object returned by `w3cHtmlValidator.validate()`.
- **options** (object) - Optional - Configuration options for the reporter.
  - **continueOnFail** (boolean) - Optional - Defaults to `false`. If `true`, messages are reported but an error is not thrown if validation fails.
  - **maxMessageLen** (number) - Optional - Trim validation messages to not exceed this length.
  - **quiet** (boolean) - Optional - Defaults to `false`. Suppress status messages for successful validations.
  - **title** (string) - Optional - Override the display title. Useful for naming HTML string inputs.
```

--------------------------------

### Validate HTML Programmatically

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Import and execute the validate function. Throttle calls to avoid rejection by the W3C server.

```javascript
import { w3cHtmlValidator } from 'w3c-html-validator';

const options = { filename: 'docs/index.html' };
w3cHtmlValidator.validate(options).then(console.log);  //outputs the resutls object
```

```javascript
w3cHtmlValidator.validate(options).then(w3cHtmlValidator.reporter);
```

--------------------------------

### w3cHtmlValidator.reporter(results, options)

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=dependents

Displays formatted validation results to the console.

```APIDOC
## w3cHtmlValidator.reporter(results, options)

### Description
Processes and displays the results object returned by the validate function.

### Parameters
#### Request Body
- **continueOnFail** (boolean) - Optional - Report messages but do not throw an error if validation failed (default: false)
- **maxMessageLen** (number) - Optional - Trim validation messages to not exceed a maximum length
- **quiet** (boolean) - Optional - Suppress status messages for successful validations (default: false)
- **title** (string) - Optional - Override display title
```

--------------------------------

### Default Ignore List

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=dependencies

Describes the `--default-rules` flag and the default opinionated ignore list for skipping unhelpful validation messages.

```APIDOC
## Default Ignore List

### Description
The `--default-rules` flag enables an opinionated, pre-defined list of messages considered unhelpful. This helps to reduce noise from common, often irrelevant, validation warnings.

### Method
CLI Flag: `--default-rules`

### Endpoint
N/A (CLI Usage)

### Parameters
#### Default Ignore Patterns
- **`with computed level`** (Level: **error**) - Explanation: Ignores messages related to outline issues when using `<aside>` with `<h2>`.
- **`Section lacks heading.`** (Level: **warning**) - Explanation: Ignores warnings about sections lacking headings, as this rule is often impractical for modern UI development.
```

--------------------------------

### Configuration: Ignore Messages

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=readme

Explains how to configure the validator to ignore specific validation messages using regex patterns or default rule sets.

```APIDOC
## Configuration: Ignore Messages

### Description
This section details how to configure the `w3c-html-validator` to ignore certain validation messages, either through custom regular expressions or a default list of opinionated rules.

### Ignore Patterns (Regex)
Custom regex patterns can be provided in the `ignoreMessages` option to skip specific validation messages.

#### Example Patterns
- `/^Duplicate ID/`
- `/^Element .blockquote. not allowed/`
- `/^Element .style. not allowed/`

### Default Ignore List
The `--default-rules` flag (or `defaultRules` option) applies a pre-defined list of messages considered unhelpful.

#### Default Rules Table
| Pattern              | Level   | Explanation                                                                                                |
|----------------------|---------|------------------------------------------------------------------------------------------------------------|
| `with computed level`| **error** | Ignores issues related to computed outline levels when using elements like `<aside>` with `<h2>`.             |
| `Section lacks heading.` | **warning** | Ignores warnings about sections lacking headings, which can be overly strict for modern UI components. |

*Note: The `ignoreMessages` and `ignoreLevel` options only function when the `output` is set to `'json'`.
```

--------------------------------

### Configure Ignore Rules

Source: https://www.npmjs.com/package/w3c-html-validator

Regex patterns used to filter out specific validation messages.

```text
/^Duplicate ID/
/^Element .blockquote. not allowed/
/^Element .style. not allowed/
```

--------------------------------

### Ignore Configuration

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=versions

Details on how to configure the validator to ignore specific validation messages using regular expressions or a default list.

```APIDOC
## Ignore Config for w3c-html-validator

### Description
This section explains how to configure the validator to ignore certain validation messages. You can use regular expressions to match specific patterns at the beginning of a message, or utilize a default list of opinionated ignore rules.

### Method
Configuration is done via the `ignoreMessages` and `defaultRules` options when calling `w3cHtmlValidator.validate()`.

### Endpoint
N/A (Programmatic Usage)

### Parameters
#### `ignoreMessages` Option
- **ignoreMessages** (array) - Required/Optional - Skip messages containing a string or matching a regex. Defaults to `[]`.
  - Each element in the array can be a string (exact match) or a regular expression.

#### `defaultRules` Option
- **defaultRules** (boolean) - Required/Optional - Apply additional built-in opinionated ignore list. Defaults to `false`.

### Ignore Patterns Example
```regex
/^Duplicate ID/
/^Element .blockquote. not allowed/
/^Element .style. not exceed/
```

The caret (`^`) regex operator matches the beginning of the validation message. The dot (`.`) regex operator matches any single character.

### Default Ignore List
When `defaultRules` is set to `true`, the following messages are ignored:

| Pattern              | Level   | Explanation                                                                                                   |
|----------------------|---------|---------------------------------------------------------------------------------------------------------------|
| `with computed level`| **error** | It's ridiculous that adding an `<aside>` with an `<h2>` breaks the outer flow's outline.                        |
| `Section lacks heading.` | **warning** | Rule is sensible for traditional print publishing but absurd for modern UI components not burning in nested `<div>` hell. |

*Note: The `ignoreMessages` and `ignoreLevel` options only work for `'json'` output. Setting `ignoreLevel` to `'warning'` skips both `'warning'` level and `'info'` level validation messages.
```

--------------------------------

### w3cHtmlValidator.reporter(results, options)

Source: https://www.npmjs.com/package/w3c-html-validator

Formats and reports the results of the validation process.

```APIDOC
## w3cHtmlValidator.reporter(results, options)

### Description
Displays formatted output for validation results.

### Parameters
#### Request Body
- **continueOnFail** (boolean) - Optional - Report messages but do not throw an error if validation failed (default: false)
- **maxMessageLen** (number) - Optional - Trim validation messages to not exceed a maximum length
- **quiet** (boolean) - Optional - Suppress status messages for successful validations (default: false)
- **title** (string) - Optional - Override display title
```

--------------------------------

### Set Validation Delay

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=code

Control the rate of validation by setting a debounce delay in milliseconds between processing files using the --delay flag.

```bash
html-validator docs --delay=200
```

--------------------------------

### w3cHtmlValidator.validate(options)

Source: https://www.npmjs.com/package/w3c-html-validator?activeTab=dependents

Validates HTML content from a file, string, or website URL against the W3C validation service.

```APIDOC
## w3cHtmlValidator.validate(options)

### Description
Validates HTML content. Note that multiple calls should be throttled to avoid rejection by the W3C server.

### Parameters
#### Request Body
- **checkUrl** (string) - Optional - W3C validation API endpoint (default: 'https://validator.w3.org/nu/')
- **defaultRules** (boolean) - Optional - Apply additional built-in opinionated ignore list (default: false)
- **dryRun** (boolean) - Optional - Bypass validation (default: false)
- **filename** (string) - Optional - HTML file to validate
- **html** (string) - Optional - HTML string to validate
- **ignoreLevel** ('info' or 'warning') - Optional - Skip unwanted messages
- **ignoreMessages** (array) - Optional - Skip messages containing a string or matching a regex
- **output** ('json' or 'html') - Optional - Get results as an array or as a web page (default: 'json')
- **website** (string) - Optional - URL of website to validate

### Response
#### Success Response (200)
- **validates** (boolean) - Whether the HTML is valid
- **mode** ('html' | 'filename' | 'website') - The input mode used
- **html** (string | null) - The HTML string if provided
- **filename** (string | null) - The filename if provided
- **website** (string | null) - The website URL if provided
- **output** ('json' | 'html') - The output format
- **status** (number) - HTTP status code
- **messages** (array | null) - Validation messages for 'json' output
- **display** (string | null) - Formatted output for 'html' output
- **dryRun** (boolean) - Whether it was a dry run
```

--------------------------------

### w3cHtmlValidator.validate(options)

Source: https://www.npmjs.com/package/w3c-html-validator

Validates HTML content from a file, string, or website URL using the W3C validation service.

```APIDOC
## w3cHtmlValidator.validate(options)

### Description
Validates HTML content. Note that multiple calls should be throttled to avoid rejection by the W3C server.

### Parameters
#### Request Body
- **checkUrl** (string) - Optional - W3C validation API endpoint (default: 'https://validator.w3.org/nu/')
- **defaultRules** (boolean) - Optional - Apply additional built-in opinionated ignore list (default: false)
- **dryRun** (boolean) - Optional - Bypass validation (default: false)
- **filename** (string) - Optional - HTML file to validate
- **html** (string) - Optional - HTML string to validate
- **ignoreLevel** ('info' or 'warning') - Optional - Skip unwanted messages
- **ignoreMessages** (array) - Optional - Skip messages containing a string or matching a regex
- **output** ('json' or 'html') - Optional - Get results as an array or as a web page (default: 'json')
- **website** (string) - Optional - URL of website to validate

### Response
#### Success Response (200)
- **validates** (boolean) - Whether the HTML is valid
- **mode** ('html' | 'filename' | 'website') - The input mode used
- **messages** (array) - Validation messages for 'json' output
- **display** (string) - Formatted output for 'html' output
```
Tokens:
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