Next.js TypeError: DOMPurify.sanitize() is Not a Function - Fix & Troubleshooting Guide

Table of Contents#

1. Understanding the Error
2. Common Causes of the Error
3. Step-by-Step Fixes
   • Fix 1: Verify DOMPurify Installation
   • Fix 2: Correct Import Statements
   • Fix 3: Handle Server-Side Rendering (SSR) Limitations
   • Fix 4: Resolve Version Conflicts
   • Fix 5: Check for Typos or Misnaming
4. Advanced Troubleshooting
5. Prevention Tips to Avoid Future Errors
6. Conclusion
7. References

1. Understanding the Error#

The error TypeError: DOMPurify.sanitize() is not a function occurs when the JavaScript engine tries to call the sanitize method on the DOMPurify object but cannot find it. This typically means:

• DOMPurify is not imported correctly.
• The library is not installed in your project.
• The code is running in an environment where DOMPurify (or its dependencies) is unavailable (e.g., server-side rendering in Next.js).
• There’s a version mismatch or a typo in your code.

Example Error Stack Trace#

TypeError: DOMPurify.sanitize is not a function  
    at HomePage (./pages/index.js:15:20)  
    at renderWithHooks (./node_modules/react-dom/cjs/react-dom-server.browser.development.js:5658:16)  
    ...  

2. Common Causes of the Error#

Before diving into fixes, let’s identify the most likely culprits:

3. Step-by-Step Fixes#

Let’s resolve the error with targeted solutions, starting with the most common causes.

Fix 1: Verify DOMPurify Installation#

The first check is ensuring DOMPurify is installed in your project.

How to Fix:#

1. Check package.json: Look for dompurify in the dependencies or devDependencies section. If missing, install it.

   // package.json (example)  
   "dependencies": {  
     "dompurify": "^3.0.6", // Should appear here  
     "next": "14.0.3",  
     "react": "18.2.0"  
   }  

2. Install DOMPurify (if missing):

   # Using npm  
   npm install dompurify  
    
   # Using yarn  
   yarn add dompurify  
    
   # Using pnpm  
   pnpm add dompurify  

3. Reinstall if corrupted: If dompurify exists in package.json but the error persists, delete node_modules and package-lock.json/yarn.lock, then reinstall:

   rm -rf node_modules package-lock.json  
   npm install  

Fix 2: Correct Import Statements#

DOMPurify uses a default export, not named exports. Importing it incorrectly is a frequent source of the sanitize is not a function error.

Common Mistake:#

// ❌ Incorrect: Using named import  
import { sanitize } from 'dompurify';  
 
// ❌ Incorrect: Trying to destructure from a default import  
import DOMPurify from 'dompurify';  
const { sanitize } = DOMPurify; // Fails if DOMPurify is not loaded  

Correct Import:#

// ✅ Correct: Import the default export  
import DOMPurify from 'dompurify';  
 
// Usage  
const sanitizedHTML = DOMPurify.sanitize('<script>malicious code</script>');  

Fix 3: Handle Server-Side Rendering (SSR) Limitations#

Next.js renders pages server-side (SSR) or at build time (SSG/ISR) by default. DOMPurify depends on browser-specific APIs like window and document, which are unavailable in Node.js (the server environment). This causes DOMPurify to load incorrectly or return undefined server-side, leading to the error.

Solutions for SSR/SSG:#

Option 1: Use dynamic Import with ssr: false#

Next.js’s dynamic import lets you load components/client-side libraries only in the browser, bypassing server-side execution.

// pages/index.js  
import dynamic from 'next/dynamic';  
 
// Dynamically import DOMPurify with SSR disabled  
const DOMPurify = dynamic(() => import('dompurify'), {  
  ssr: false, // Load only on the client  
  loading: () => <p>Loading...</p>, // Optional loading state  
});  
 
export default function HomePage({ userContent }) {  
  // Sanitize only after DOMPurify loads (client-side)  
  const sanitizedContent = DOMPurify.sanitize(userContent);  
 
  return <div dangerouslySetInnerHTML={{ __html: sanitizedContent }} />;  
}  

Option 2: Check for window Availability#

Wrap DOMPurify usage in a check for the window object (available only in browsers) to avoid server-side execution.

// pages/index.js  
import DOMPurify from 'dompurify';  
 
export default function HomePage({ userContent }) {  
  // Only run sanitization on the client  
  if (typeof window !== 'undefined') {  
    const sanitizedContent = DOMPurify.sanitize(userContent);  
    return <div dangerouslySetInnerHTML={{ __html: sanitizedContent }} />;  
  }  
 
  // Return fallback for server-side (empty or loading state)  
  return <div>Loading content...</div>;  
}  

Option 3: Use useEffect for Client-Side Execution#

For React components, useEffect runs after the component mounts (client-side), ensuring window is available.

// components/SanitizedContent.js  
import { useEffect, useState } from 'react';  
import DOMPurify from 'dompurify';  
 
export default function SanitizedContent({ html }) {  
  const [sanitizedHTML, setSanitizedHTML] = useState('');  
 
  useEffect(() => {  
    // Run only on the client (useEffect doesn't run server-side)  
    setSanitizedHTML(DOMPurify.sanitize(html));  
  }, [html]);  
 
  return <div dangerouslySetInnerHTML={{ __html: sanitizedHTML }} />;  
}  

Fix 4: Resolve Version Conflicts#

Older versions of DOMPurify may have breaking changes. For example, versions prior to 2.0.0 had different method names or behavior.

Check Your DOMPurify Version:#

npm list dompurify  
# or  
yarn list dompurify  

Update to the Latest Version:#

# npm  
npm update dompurify  
 
# yarn  
yarn upgrade dompurify  
 
# pnpm  
pnpm update dompurify  

Note: Always check the DOMPurify release notes when updating to avoid unexpected changes.

Fix 5: Check for Typos or Misnaming#

A simple typo can cause the error. Double-check:

• The method name: sanitize (not sanitise, sanitaze, or purify).
• The library name: DOMPurify (case-sensitive; not dompurify or DomPurify in variable names).

// ❌ Typo example  
const sanitized = DOMPurify.sanitise(userInput); // "sanitise" (British spelling)  
 
// ✅ Correct  
const sanitized = DOMPurify.sanitize(userInput);  

4. Advanced Troubleshooting#

If the above fixes don’t resolve the error, try these advanced steps:

Check Imported Object Structure#

Log DOMPurify to the console to verify its structure. If it’s undefined or an empty object, the import/loading process is failing.

import DOMPurify from 'dompurify';  
 
console.log('DOMPurify:', DOMPurify); // Check browser console (F12)  

Expected Output (client-side):

DOMPurify: { sanitize: ƒ, addHook: ƒ, ... }  

If DOMPurify is undefined, revisit Fix 3 (SSR issues) or Fix 1 (installation).

Verify Browser Environment#

If using DOMPurify in a non-component file (e.g., lib/utils.js), ensure it’s only called client-side. Use a guard clause to check for window:

// lib/sanitize.js  
import DOMPurify from 'dompurify';  
 
export function sanitizeHTML(html) {  
  if (typeof window === 'undefined') {  
    return ''; // Return empty or fallback for server-side  
  }  
  return DOMPurify.sanitize(html);  
}  

Check for Tree Shaking or Bundler Conflicts#

Rarely, Next.js’s Webpack bundler may tree-shake DOMPurify (remove unused code) if it’s not imported correctly. Ensure the import is not wrapped in unused conditionals or dynamic logic that Webpack misinterprets.

Use a CDN as a Fallback#

As a last resort, load DOMPurify via a CDN in _document.js to ensure it’s available globally:

// pages/_document.js  
import Document, { Html, Head, Main, NextScript } from 'next/document';  
 
export default class MyDocument extends Document {  
  render() {  
    return (  
      <Html>  
        <Head>  
          {/* Load DOMPurify from CDN */}  
          <script src="https://cdnjs.cloudflare.com/ajax/libs/dompurify/3.0.6/purify.min.js"></script>  
        </Head>  
        <body>  
          <Main />  
          <NextScript />  
        </body>  
      </Html>  
    );  
  }  
}  
 
// Usage in components (access via window.DOMPurify)  
const sanitized = window.DOMPurify.sanitize(html);  

5. Prevention Tips to Avoid Future Errors#

1. Pin DOMPurify Version: Use a specific version in package.json (e.g., dompurify: "3.0.6") instead of ^ to avoid accidental updates with breaking changes.
2. Add Type Safety (TypeScript): Install @types/dompurify for auto-complete and type checks:

   npm install -D @types/dompurify  

3. Test SSR/Client-Side Behavior: Use next dev and next build && next start to test both development and production modes (SSR issues often surface in production).
4. Lint Imports: Use ESLint with eslint-plugin-import to flag incorrect import statements.
5. Document Sanitization Logic: Add comments in utility functions (e.g., // DOMPurify: Loaded client-side only) to remind teammates of SSR limitations.

6. Conclusion#

The TypeError: DOMPurify.sanitize() is not a function error in Next.js is almost always caused by one of four issues: missing installation, incorrect imports, server-side rendering conflicts, or typos. By following the step-by-step fixes in this guide—starting with verifying installation and imports, then addressing SSR limitations—you can resolve the error and ensure your application safely sanitizes HTML.

Remember: DOMPurify is a client-side library, so always guard its usage against server-side execution in Next.js. With proper setup, you’ll keep your app secure and error-free.

7. References#

• DOMPurify Official Documentation
• Next.js Dynamic Imports
• Next.js SSR/SSG Documentation
• MDN: Window Object
• @types/dompurify on npm