Angular Zone-Aware Task Scheduler

This challenge focuses on implementing a task scheduler within an Angular application that leverages Angular's NgZone to ensure tasks are executed within the Angular zone. This is crucial for maintaining proper change detection and preventing unexpected behavior when dealing with asynchronous operations outside of Angular's normal lifecycle. You'll build a service that schedules tasks and guarantees they run within the Angular zone.

Problem Description

You are tasked with creating an ZoneSchedulerService that allows scheduling tasks to be executed. The service should provide a method scheduleTask(task: () => void, delay: number) which schedules a task to be executed after a specified delay (in milliseconds). Crucially, the task must be executed within the Angular zone. This means that any changes made by the task should trigger Angular's change detection mechanism.

Key Requirements:

• Zone Execution: All scheduled tasks must be executed within the Angular zone.
• Delay: The task should be executed after the specified delay.
• Error Handling: The service should handle potential errors during task execution gracefully.
• Cancellation (Optional): While not strictly required, consider how you might allow cancellation of scheduled tasks.

Expected Behavior:

When scheduleTask is called, a timer should be set. After the delay, the provided task function should be executed within the Angular zone. If the task throws an error, the error should be caught and logged (but not re-thrown).

Edge Cases to Consider:

• What happens if the delay is 0?
• What happens if the task throws an error?
• What happens if the component that scheduled the task is destroyed before the task executes? (While not required to prevent this, consider how it might affect the application).
• What happens if NgZone is not available (e.g., in a non-Angular environment)?

Examples

Example 1:

Input: scheduleTask(() => { console.log("Task 1 executed"); }, 1000);
Output: (After 1 second) "Task 1 executed" logged to the console. Angular change detection is triggered if the task modifies component properties.
Explanation: The task is scheduled and executed after a 1-second delay within the Angular zone.

Example 2:

Input: scheduleTask(() => { throw new Error("Task failed!"); }, 500);
Output: (After 0.5 seconds) Error "Task failed!" is logged to the console. Angular change detection is *not* triggered because the error prevents the task from completing.
Explanation: The task is scheduled, but throws an error. The error is caught and logged, preventing the application from crashing.

Example 3:

Input: scheduleTask(() => { console.log("Task 2 executed"); }, 0);
Output: (Immediately) "Task 2 executed" logged to the console. Angular change detection is triggered if the task modifies component properties.
Explanation: The task is scheduled and executed immediately within the Angular zone.

Constraints

• The service must be written in TypeScript and compatible with Angular.
• The delay must be a non-negative number (0 or greater).
• The task function must be a function with no arguments and no return value (() => void).
• The service should not introduce any significant performance overhead. Avoid unnecessary computations or memory allocations.
• The service should be designed to be reusable across different Angular components.

Notes

• You'll need to inject NgZone into your service.
• Consider using setTimeout or setInterval to implement the delay. Remember to clear the timer if the component is destroyed to prevent memory leaks.
• Think about how to handle errors gracefully to prevent the application from crashing.
• While cancellation is optional, it's a good practice to consider how it could be implemented. You could use a flag to indicate whether a task should be executed or not.
• Focus on ensuring the task is executed within the Angular zone. This is the core requirement of the challenge.