Comment by AnkhMorporkian

For anyone actually looking to transpile Python into Javascript for web usage, please take a look at Transcrypt[1]. It's the only Py->JS Compiler that creates reasonable output sizes, readable code, and doesn't require loading a virtual machine.

1: http://transcrypt.org/

Edit: Shouldn't have said virtual machine, I meant a large runtime, though obviously a few implementations do have a proper VM.