Now we respond dynamically to changes in the location hash in the URL
bar. It means that you can do links in HTML as `<a
href=“#HelloThere”>go</a>` and in Markdown as `[example
link](#HelloThere).`
We still need to make startup.js more modular
We re-use some of the existing syncer mechanism. It was already keeping
track of changes to tiddlers in the store when working with a tiddler
syncadaptor. Now it also tracks changes when there is no syncadaptor,
allowing us to provide a warning if there are unsaved changes.
