This is JavaScript, so there are probably tons of weird edge cases, but basically, within a with (expr) { … } block, everything defined on expr is put in scope:

This is JavaScript, so there are probably tons of weird edge cases, but basically, within a with (expr) { … } block, everything defined on expr is put in scope: with (Math) with (console) log(PI) It reminds me a bit of Clojure's doto.