Simplified version of createSignal

createSignalMock.js

function createSignal(initialValue) {
  let value = initialValue; // Internal state to hold the current value of the signal
  const subscribers = new Set(); // Set to keep track of subscribers (components or functions that depend on the signal)

  // Getter function to retrieve the current value of the signal
  function get() {
    return value;
  }

  // Setter function to update the value of the signal and notify subscribers
  function set(newValue) {
    value = newValue; // Update the internal state with the new value
    // Notify all subscribers by calling their update functions
    subscribers.forEach(subscriber => subscriber());
  }

  // Function to subscribe to the signal and receive updates
  function subscribe(updateFunction) {
    subscribers.add(updateFunction); // Add the update function to the subscribers set
    // Return a function to unsubscribe and remove the update function from subscribers set
    return () => subscribers.delete(updateFunction);
  }

  // Return the getter, setter, and subscribe functions as an array
  return [get, set, subscribe];
}

// Example usage:
const [count, setCount, subscribe ] = createSignal(0);

console.log('count: ', count()); // 0

setCount(12); // update the state

console.log('count: ', count()); // 12