Zone-less Angular Application Challenge

Angular applications typically rely on the Zone.js library to automatically detect changes and trigger change detection cycles. However, in certain scenarios, especially when integrating with third-party libraries that don't play well with Zone.js or when aiming for finer-grained control over change detection, you might want to build an Angular application without Zone.js. This challenge tasks you with creating a basic Angular application that functions correctly without Zone.js.

Problem Description

Your goal is to create a simple Angular application that demonstrates the ability to manage change detection manually, without relying on Zone.js. This involves understanding how Angular's change detection mechanism works and how to trigger it explicitly when needed.

Key Requirements:

1. No Zone.js: The application must run without Zone.js being imported or used in any way.
2. Manual Change Detection: You need to implement a mechanism to manually trigger change detection.
3. Basic Functionality: The application should have a component that displays some data, and this data should be updated and reflected in the UI.
4. Dependency Injection: Demonstrate that Angular's dependency injection system still works in a zone-less context.

Expected Behavior:

• A component should render some initial data.
• An action (e.g., a button click) should trigger a change in the component's data.
• The UI must update to reflect the changed data only after manual change detection is triggered.

Edge Cases to Consider:

• Asynchronous operations (e.g., setTimeout) will not automatically trigger change detection. You will need to handle these explicitly.

Examples

Example 1: Basic Data Display and Update

// Assume a simple component structure
// Initial data: { message: 'Hello, Zone-less World!' }
// Button: "Update Message"

Output:

Initially, the UI displays: "Hello, Zone-less World!". After clicking the "Update Message" button, the UI remains unchanged until manual change detection is triggered. After manual change detection, the UI updates to display the new message, e.g., "Message Updated!".

Explanation:

The component's data is changed, but without Zone.js, Angular doesn't know to re-render the view. Manual intervention is required to tell Angular to check for changes and update the DOM.

Example 2: Asynchronous Update

// Assume a component with a button that triggers a setTimeout after 1 second.
// Initial data: { count: 0 }
// Button: "Increment after delay"

Output:

Initially, the UI displays: "Count: 0". Clicking the "Increment after delay" button starts a 1-second timer. After 1 second, the internal count variable increments to 1. The UI does not update automatically. If manual change detection is triggered after the delay, the UI updates to display: "Count: 1".

Explanation:

setTimeout is an asynchronous operation. In a zone-less app, this asynchronous task completing does not inherently signal Angular to check for changes. You must manually initiate the change detection cycle after the asynchronous operation completes and potentially modifies data.

Constraints

• Angular Version: Use Angular 14 or later.
• Language: TypeScript only.
• No Zone.js: zone.js should not be a dependency or imported in any application file.
• Build Process: The build process should not include zone.js for runtime.

Notes

• You will likely need to configure your Angular application's main.ts or polyfills.ts to exclude Zone.js.
• Consider how you will access the ChangeDetectorRef to manually trigger change detection.
• Think about how you will handle asynchronous operations that modify component state.
• This challenge focuses on the core principles of zone-less Angular. Libraries that heavily rely on Zone.js for their internal change detection might require additional wrappers or modifications.