Forgets the catalogue, for a page that loads a different icon set later.
What is known right now, without waiting.
Empty until Load has finished, which is the honest answer: a caller that rendered this before the fonts arrived would draw the short fallback list and then replace it, which reads as the picker changing its mind.
True when the built-in list is standing in because the page could not be read.
Every icon on offer, with the style that draws it.
Each style has to be FETCHED before it can be measured. A browser loads a web font only when something on the page uses it, so an app drawing solid icons has the solid font and neither of the others — and measuring then reports every brands and regular icon as missing, which is most of the catalogue.
Falls back to a short built-in list when the stylesheets cannot be read — a
cross-origin sheet without CORS headers throws on cssRules — or when reading them
fails in any other way, so the picker always has something to show.
The Font Awesome icons this page can draw, worked out once and shared.
Answering it means walking every CSS rule in the document and then measuring a couple of thousand glyphs, so it is done on first ask and kept. A picker that recomputed per open would stall each time it was used.