Introduction

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Validate your SSR/SSG HTML automatically to catch hydration and accessibility issues before they ship.

Key features

Zero-configuration required
Helps reduce hydration errors
Detects common accessibility mistakes

This module configures html-validate to automatically validate Nuxt server-rendered HTML (SSR and SSG) to detect common issues with HTML that can lead to hydration errors, as well as improve accessibility and best practice.

Quick start

Install

Terminal

npx nuxi@latest module add html-validator

Configure Nuxt

defineNuxtConfig({
  modules: ['@nuxtjs/html-validator']
})

export default {
  buildModules: ['@nuxtjs/html-validator']
}

export default {
  // Install @nuxtjs/html-validator as a dependency instead of devDependency
  modules: ['@nuxtjs/html-validator']
}

html-validator won't be added to your production bundle — it's only used in development and at build/generate time.

Configuration

@nuxtjs/html-validator exposes four options:

usePrettier enables prettier printing of your source code to show errors in-context.

Consider not enabling this if you are using TailwindCSS, as prettier will struggle to cope with parsing the size of your HTML in development mode.

logLevel sets the verbosity to one of verbose, warning or error. It defaults to verbose in dev, and warning when generating.

Use this option to turn off console logging for the No HTML validation errors found for ... message.

failOnError will throw an error after running nuxt generate if there are any validation errors with the generated pages.

Useful in continuous integration.

options allows you to pass in html-validate options that will be merged with the default configuration.

You can find more about configuring html-validatehere.

Defaults

nuxt.config.ts

{
htmlValidator: {
  usePrettier: false,
  logLevel: 'verbose',
  failOnError: false,
  /** A list of routes to ignore (that is, not check validity for). */
  ignore: [/\\.(xml|rss|json)$/],
  options: {
    extends: [
      'html-validate:document',
      'html-validate:recommended',
      'html-validate:standard'
    ],
    rules: {
      'svg-focusable': 'off',
      'no-unknown-elements': 'error',
      // Conflicts or not needed as we use prettier formatting
      'void-style': 'off',
      'no-trailing-whitespace': 'off',
      // Conflict with Nuxt defaults
      'require-sri': 'off',
      'attribute-boolean-style': 'off',
      'doctype-style': 'off',
      // Unreasonable rule
      'no-inline-style': 'off'
    }
  }
}
}

You're good to go!

Every time you hard-refresh (server-render) a page in Nuxt, you will see any HTML validation issues printed in your server console.