Browsers do a fast partial parse to figure out things like scoping and variable names, but skip actually building an AST so it's still a lot quicker than full p

Browsers do a fast partial parse to figure out things like scoping and variable names, but skip actually building an AST so it's still a lot quicker than full parsing (e.g. https://v8.dev/blog/preparser https://v8.dev/blog/preparser)