Stage 04 of six
Rendering
Bytes arrive in chunks and the browser does not wait for the last of them. It builds a tree while the document is still downloading, then holds the paint until it knows the rules.
-
The critical path
Stylesheets block rendering because nothing can be laid out until the rules are known, and a font can hold text invisible while it loads.
-
Reflow and repaint
Changing geometry costs far more than changing colour, and knowing which is which is most of performance work.
-
Parsing before the download ends
The tree is built incrementally, which is why a badly placed script stalls everything.
The rest of the chain
Five other stages01 Origins
One machine at CERN.
02 Resolution
Turning a name into an address.
03 Trust
Why the padlock means anything.
05 The Cascade
Which rule actually wins.
06 Where Browsers Differ
The gap between spec and behaviour.