Pros of DOMPurify

• Designed specifically for client-side sanitization in browsers
• Faster performance due to DOM-based approach
• More extensive configuration options for fine-tuned control

Cons of DOMPurify

• Larger file size, which may impact page load times
• Limited server-side support compared to Bleach

Code Comparison

Bleach:

import bleach

dirty_html = '<script>alert("XSS")</script><p>Safe content</p>'
clean_html = bleach.clean(dirty_html)

DOMPurify:

import DOMPurify from 'dompurify';

const dirty_html = '<script>alert("XSS")</script><p>Safe content</p>';
const clean_html = DOMPurify.sanitize(dirty_html);

Key Differences

• Bleach is Python-based and primarily for server-side use, while DOMPurify is JavaScript-based for client-side sanitization
• Bleach uses string manipulation, whereas DOMPurify leverages the browser's DOM parser
• DOMPurify offers more granular control over allowed tags and attributes

Use Cases

• Choose Bleach for server-side sanitization in Python applications
• Opt for DOMPurify when working with client-side JavaScript and need browser-specific features

Both libraries effectively sanitize HTML and prevent XSS attacks, but their ideal use cases differ based on the development environment and specific project requirements.

Pros of js-xss

• Specifically designed for JavaScript, making it more suitable for client-side XSS prevention
• Offers flexible configuration options for customizing allowed tags and attributes
• Provides a whitelist-based approach, which can be more secure in certain scenarios

Cons of js-xss

• Less comprehensive documentation compared to Bleach
• May require more manual configuration to achieve desired results
• Not as widely adopted or battle-tested as Bleach

Code Comparison

Bleach (Python):

import bleach

html = '<script>alert("XSS")</script><p>Safe content</p>'
cleaned = bleach.clean(html, tags=['p'])
print(cleaned)  # Output: &lt;script&gt;alert("XSS")&lt;/script&gt;<p>Safe content</p>

js-xss (JavaScript):

const xss = require('xss');

const html = '<script>alert("XSS")</script><p>Safe content</p>';
const cleaned = xss(html);
console.log(cleaned);  // Output: &lt;script&gt;alert("XSS")&lt;/script&gt;<p>Safe content</p>

Both libraries effectively sanitize HTML input by removing potentially dangerous tags and attributes. Bleach is more suitable for server-side Python applications, while js-xss is tailored for JavaScript environments, particularly in the browser. The choice between them depends on the specific programming language and environment of your project.

Pros of Sanitize

• More flexible configuration options for allowed elements and attributes
• Supports custom filters for fine-grained control over sanitization
• Actively maintained with regular updates and improvements

Cons of Sanitize

• Slower performance compared to Bleach, especially for large inputs
• Less extensive documentation and community support
• Steeper learning curve for advanced usage

Code Comparison

Bleach:

import bleach

html = '<script>alert("XSS")</script><p>Safe content</p>'
clean_html = bleach.clean(html, tags=['p'], strip=True)

Sanitize:

require 'sanitize'

html = '<script>alert("XSS")</script><p>Safe content</p>'
clean_html = Sanitize.fragment(html, Sanitize::Config::BASIC)

Both libraries effectively remove the malicious script tag, but Sanitize offers more configuration options out of the box. Bleach requires additional setup for similar flexibility. Sanitize's default configurations (like BASIC) provide quick, pre-defined sanitization levels, while Bleach often requires manual specification of allowed tags and attributes.

Pros of Caja

• More comprehensive security model, including object-capability security
• Supports JavaScript sandboxing in addition to HTML sanitization
• Offers a wider range of features for content rewriting and transformation

Cons of Caja

• More complex to set up and use compared to Bleach
• Less actively maintained (last update in 2017)
• Steeper learning curve due to its extensive feature set

Code Comparison

Bleach (HTML sanitization):

import bleach

html = '<script>alert("XSS")</script><p>Safe content</p>'
clean_html = bleach.clean(html)
print(clean_html)  # Output: &lt;script&gt;alert("XSS")&lt;/script&gt;<p>Safe content</p>

Caja (JavaScript sanitization):

var cajaServer = require('google-caja');
var html = '<script>alert("XSS")</script><p>Safe content</p>';
cajaServer.sanitize(html, function(sanitizedHtml) {
  console.log(sanitizedHtml);
});

Summary

Bleach is a simpler, more focused library for HTML sanitization, while Caja offers a broader set of security features including JavaScript sandboxing. Bleach is more actively maintained and easier to use, making it a better choice for straightforward HTML cleaning tasks. Caja, despite being more complex, provides a more comprehensive security solution for applications requiring advanced content rewriting and transformation capabilities.