url-observer.md

On init,

1. Listen for load event
2. Listen for hashchange event
3. Listen for popstate event
4. Listen for manual pushState event
5. Intercept all link clicks

On load event

1. Extract URL info
2. Compare and run internal URL update if needed

On popstate event

1. Extract URL info
2. Compare and run internal URL update if needed

On hashchange event

1. Extract the latest hash from URL
2. Compare and run internal URL update with before route change handler if needed

On manual pushState event

1. Extract URL info
2. Compare and run internal URL update with before route change handler if needed

On link click

1. Check if the link should be intercepted
2. Continue to 3. for intercept-able link
3. Extract URL info from link's href
4. Compare and run internal URL update with before route change handler if needed

Internal URL update

1. When skipCheck=false, compare the old and new route to determine if route change is needed.
2. Continue to 3. for a new route
3. Continue to 4. for a matched route, else run http-404 handler.
4. Find matched route then fire manual pushState event with the route matched keys

Internal URL update with before route change handler

1. Compare old and new route to determine if route change is needed
2. Find before route change handler for the current route and continue to 3. if found one. Else, skip to 4.
3. Execute before route change handler and wait for route change approval. Continue to 4. for an approved route change.
4. Run internal URL update with skipCheck=true.

404 handler

1. Fire manual pushState event with notFound=true to notify a not-found route

Internal URL update with before route change handler

1. Find matched route
2. If matched route, fire URL change event with matched groups
3. Else, run 404 route handler for a not-found route