Event Loop Simulator in JavaScript

Understanding the JavaScript event loop is crucial for mastering asynchronous programming. This challenge asks you to build a simplified simulator of the JavaScript event loop to visualize how asynchronous operations are handled and executed. By creating this simulator, you'll gain a deeper understanding of how JavaScript manages non-blocking I/O and callbacks.

Problem Description

You are tasked with creating a JavaScript function simulateEventLoop that takes an array of asynchronous operations as input and simulates the execution of the JavaScript event loop. Each asynchronous operation will be represented as an object with the following structure:

{
  type: 'timeout', // or 'ajax', or 'interval'
  delay: 1000, // milliseconds
  callback: function() { console.log('Callback executed'); }
}

The type property indicates the type of asynchronous operation. timeout simulates a setTimeout call, ajax simulates an asynchronous network request, and interval simulates a setInterval call. The delay property specifies the delay in milliseconds before the callback is executed. The callback property is a function that will be executed when the delay is over.

Your simulateEventLoop function should:

1. Process Operations: Iterate through the input array of asynchronous operations.
2. Simulate Queuing: For each operation, simulate adding it to a queue (you can use a simple array for this purpose).
3. Simulate Execution: Simulate the event loop's behavior by processing the queue. For each operation in the queue:
   • If the operation is a timeout, ajax, or interval, wait for the specified delay using setTimeout (or a similar mechanism).
   • After the delay, execute the callback function.
   • For interval operations, re-add the operation to the queue after the delay.
4. Output: Log messages to the console to indicate the state of the event loop (e.g., "Operation added to queue", "Executing callback", "Interval operation re-queued"). The order of these logs should reflect the simulated event loop's behavior.

Examples

Example 1:

Input: [
  { type: 'timeout', delay: 500, callback: () => console.log('Timeout 1') },
  { type: 'ajax', delay: 1000, callback: () => console.log('Ajax 1') },
  { type: 'timeout', delay: 250, callback: () => console.log('Timeout 2') }
]
Output: (Console logs, order may vary slightly due to timing)
"Operation added to queue" (for each operation)
"Executing callback: Timeout 2"
"Executing callback: Timeout 1"
"Executing callback: Ajax 1"
Explanation: Timeout 2 executes first (250ms), then Timeout 1 (500ms), and finally Ajax 1 (1000ms). The console logs reflect this order.

Example 2:

Input: [
  { type: 'interval', delay: 1000, callback: () => console.log('Interval 1') }
]
Output: (Console logs, repeated indefinitely)
"Operation added to queue"
"Executing callback: Interval 1"
"Operation added to queue"
"Executing callback: Interval 1"
... (continues indefinitely)
Explanation: The interval operation is added to the queue, executed after 1 second, and then re-queued, creating an infinite loop.

Example 3: (Edge Case - Empty Input)

Input: []
Output: (No console logs)
Explanation: If the input array is empty, the function should do nothing.

Constraints

• The delay property of each operation must be a non-negative integer.
• The callback property must be a function.
• The simulator should not block the main thread indefinitely. Use setTimeout appropriately to avoid freezing the browser.
• The interval operations should be re-queued indefinitely until the simulator is explicitly stopped (this is outside the scope of this challenge, but be mindful of potential infinite loops).
• The simulator should handle multiple asynchronous operations concurrently.

Notes

• This is a simplified simulation. The real JavaScript event loop is more complex, involving microtasks, task queues, and other intricacies.
• Focus on accurately simulating the basic queuing and execution behavior of the event loop.
• Consider using setTimeout to simulate the delays. Be aware that setTimeout itself is handled by the event loop, so you're essentially simulating the event loop within the event loop.
• The order of execution for operations with the same delay might vary slightly due to timing differences. Your simulator doesn't need to guarantee a specific order in such cases.
• For the interval type, you don't need to implement a mechanism to stop the interval. Assume it runs forever.