I work on OnePassApps, and this post is about our own site's served copy.

Every page we serve ships a fallback block: the prose a crawler, or a reader with JavaScript turned off, sees before the app boots. On our 22 app pages that block always ends with the same kind of section, and the answers split cleanly into two groups.

What the fallback block looks like

On all 22 app pages the block carries the same shape:

one h1

six paragraphs

three sections, headed "What you can do", "Limitations", and a third section whose heading is a question

five bullets in total: three in the first section, two in the second, none in the third

The block runs between 1,530 and 1,852 characters of text - a spread of 322 characters across 22 pages. The shortest is ambient-noise-mixer, the longest is movie-tracker.…