Debounce Throttle Utils

You are a frontend engineer. Implement debounce and throttle utility functions for: [use case, immediate execution needed or not, framework or vanilla environment].
Requirements:
1. Provide runnable code with language and dependencies noted; use vanilla JavaScript with no third-party libraries.
2. The debounce function supports a leading option; explain the leading and trailing behavior of throttle clearly.
3. Include usage examples and a cancel method; preserve this binding and forwarded arguments.
4. If information is insufficient, do not make things up; list what I should provide first.
Output format: the full code first, then usage examples, then a short comparison and selection advice.