web-worker-csp

Web Worker CSP Example

This example demonstrates how to enable Web Worker support with Content Security Policy (CSP) in HyperServe.

What this example shows

• How to enable Web Worker support using WithCSPWebWorkerSupport()
• How to create Web Workers using blob: URLs
• How CSP headers are configured to allow Web Workers
• Simulation of real-world usage (like Tone.js audio libraries)

The Problem

Many modern web applications use Web Workers for performance optimization. Libraries like:

• Tone.js - Web Audio API library for audio synthesis
• PDF.js - PDF rendering library
• Custom audio/video processing libraries

These libraries create Web Workers using blob: URLs, which are blocked by default by Content Security Policy (CSP) for security reasons.

The Solution

HyperServe provides WithCSPWebWorkerSupport() to enable blob: URLs in the CSP worker-src and child-src directives.

Running the Example

cd examples/web-worker-csp
go run main.go

Visit: http://localhost:8080

What to Test

1. Test Web Worker - Creates a simple Web Worker using blob: URL
2. Test Tone.js (Simulated) - Simulates how Tone.js creates timing workers
3. Show CSP Headers - Displays the actual CSP headers sent by the server

Key Code

// Enable Web Worker support
srv, err := server.NewServer(
    server.WithCSPWebWorkerSupport(),
)

// Apply security headers with Web Worker support
srv.AddMiddleware("*", server.HeadersMiddleware(srv.Options))

CSP Configuration

When Web Worker support is enabled, the CSP header includes:

• worker-src 'self' blob:
• child-src 'self' blob:

When disabled (default), Web Workers with blob: URLs will be blocked.

Security Note

Web Worker support is disabled by default for security reasons. Only enable it when your application specifically needs to use Web Workers with blob: URLs.

Real-World Usage

This feature is essential for:

• Digital Audio Workstations (DAWs) using Tone.js
• PDF viewers using PDF.js
• Video/audio processing applications
• Any application using Web Workers for performance optimization