Rendering HTML Strings in Angular 2+

Introduction

Rendering HTML content dynamically is a common requirement in Angular applications, especially when dealing with user-generated content, CMS-driven applications, or integrating third-party data. However, Angular enforces strict security mechanisms to prevent XSS (Cross-Site Scripting) attacks.

In this article, we’ll explore different ways to render HTML strings in Angular and how these methods have evolved across different Angular versions.

The Default Approach: Using [innerHTML]

The easiest and most straightforward way to render HTML in Angular is through the [innerHTML] property binding. This method is safe and ensures automatic sanitization

Security Note: Angular automatically sanitizes the content, removing any potentially dangerous elements such as script tags.

Bypassing Security with DomSanitizer

There are cases where the default sanitization removes required HTML elements (like inline styles, embedded iframes, or SVGs). In such scenarios, we can use Angular’s DomSanitizer service to mark the content as safe.

Warning: Using bypassSecurityTrustHtml() exposes your app to XSS vulnerabilities. Use it only when you fully trust the HTML content.

Evolution of HTML Rendering in Angular (Version-Wise)

Now, let’s take a look at how HTML rendering in Angular has changed over the years.

Angular 2 – 4

Introduced [innerHTML] for safe HTML rendering.

DomSanitizer was introduced to allow bypassing security.
Security: Basic sanitization applied by default.

Angular 5 – 8

Security Enhancements:

• Stricter sanitization rules were implemented.
• More elements were automatically removed for safety.

Rendering Process: No syntax changes, but better performance improvements.

Angular 9 – 11

Security Improvements:

• Stricter warnings for unsafe HTML.
• Still requires DomSanitizer for explicitly trusted content.

Angular 12 – 14

Better Performance:

• Improved handling of HTML bindings.
• Faster change detection for HTML-heavy components.

Security Remains Strong:

• No major changes to [innerHTML] or DomSanitizer.

Angular 15+ (Standalone Components)

Standalone Components Introduced:

• Allows defining components without NgModules.

HTML Rendering Impact:

• No change to [innerHTML] or DomSanitizer, so the same techniques apply.

Example in a Standalone Component (Angular 15+)

Best Practices for Rendering HTML in Angular

• Use [innerHTML] when you need basic HTML rendering (e.g., formatting text).
• Use DomSanitizer cautiously—only for trusted content.
• Never trust user-generated HTML without proper sanitization.
• Optimize for performance—avoid unnecessary HTML re-renders.

Conclusion

Rendering HTML strings in Angular is easy with [innerHTML], but security should always be a priority. With every version, Angular continues to improve security, performance, and best practices. Whether working with Angular 2 or the latest version, the core methods remain the same—just with better security and efficiency!