https://github.com/CyberShadow/dscripten-tools
This builds a little upon Sebastien Alaiwan (Ace17)'s excellent prior work of putting together a toolchain for compiling D to JavaScript / asm.js.
Improvements include a DMD-like driver and rdmd wrapper, meaning that most tools that know how to use dmd/rdmd will be able to also use this toolchain. Dub is an example. Currently the focus is on headless scripts - Web Workers and Node.
Also included are some hacked up parts of Phobos/Druntime. Generally such environments are restricted to @nogc stuff, but I wanted to see how far we can get without prior restrictions. As a result, things like Appender and format(...) (i.e. formatting to the heap) work. Of course, garbage collection is unavailable - it's using the "manual" GC implementation (allocates only), though considering most webpages are short-lived, it might not be a problem for many use cases.
I heard there was a bit of general interest on the subject, so would be interesting to hear about more potential use cases.