Implement a Debounce Function

Implement a Debounce Function

Create a debounce function with TypeScript types that properly handles the this context and cleanup.

Solution:

function debounce<T extends (...args: any[]) => any>(
  func: T,
  wait: number,
  immediate?: boolean
): (...args: Parameters<T>) => void {
  let timeout: NodeJS.Timeout | null = null;
  
  return function executedFunction(this: any, ...args: Parameters<T>) {
    const later = () => {
      timeout = null;
      if (!immediate) func.apply(this, args);
    };
    
    const callNow = immediate && !timeout;
    
    if (timeout) clearTimeout(timeout);
    timeout = setTimeout(later, wait);
    
    if (callNow) func.apply(this, args);
  };
}

// Usage
const debouncedSearch = debounce(function(this: any, query: string) {
  console.log('Searching:', query);
}, 300);

// Cleanup method
function debounceWithCleanup<T extends (...args: any[]) => any>(
  func: T,
  wait: number
): T & { cancel: () => void } {
  let timeout: NodeJS.Timeout | null = null;
  
  const debounced = function(this: any, ...args: Parameters<T>) {
    if (timeout) clearTimeout(timeout);
    timeout = setTimeout(() => func.apply(this, args), wait);
  } as T & { cancel: () => void };
  
  debounced.cancel = () => {
    if (timeout) {
      clearTimeout(timeout);
      timeout = null;
    }
  };
  
  return debounced;
}