We sometimes briefly see empty files when watching

[mbostock]

It appears that sometimes we see empty files briefly when watching, which are then immediately updated with a non-empty file. The end result on the client is the same, except we end up scrolling to the top because the page is briefly empty in the interim. We should either debounce file watching in general, or specifically when the file is empty, to avoid re-evaluating the entire page and scrolling to the top. It’s okay if the reactive update is delayed by one–two hundred milliseconds.

[mbostock]

I’m seeing a lot of scroll-to-the-top behavior when editing a longer page (the new getting-started.md in #603). We should investigate what is happening here.

[mbostock]

Here’s evidence that it’s seeing the page as briefly empty: all the nodes are removed, and then immediately after another update adds them back.

[mbostock]

Also, e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 is the empty hash.