With all the improvements that have been incorporated into the emscripten build process to make builds faster and smaller, I think the Closure pass sticks out now like a sore thumb :)
The main problems are IMHO:
- It's slow, my most minimal sokol-sample which has a 51 KByte JS runtime (without closure) needs about 11 seconds for a full rebuild with closure enabled, and 4.7 seconds without closure but optimizations, and 2.5 seconds without closure and optimizations. For a single build target that's not much, but for a project with many targets (for instance my sample project has about 50 exe targets, which "blows up" to about 4 minutes without closure vs 9 minutes with closure).
- It depends on Java, which is becoming more and more an annoyance (see Oracles recent steps to take Java hostage, and it's yet another thing that must be installed).
On the other hand, Closure really reduces the Javascript runtime file dramatically, so it's a crucial step in the build process.
Are there any plans yet to eventually get rid of Closure and replace this with something less "annoying"?