It's hard, much harder than creating a native client game.
Many more access restrictions, javascript and flash were only two options in the past, and each had it problems.
I have been working on a browser based game for TOO long now, and garbage collection is a constant problem. Plus things just run a LOT slower than a native c++ client.
I'm really interested to know what the large problesm you've been facing are.
Also, if you're facing a problem with garbage collection, have you tried the emscripten/wasm approach? Using some garbage collected language and compiling it down to javascript? Or maybe even one that is functional to make garbage collection simpler?
Send me an email. Happy to talk to you about it. Just the garbage collection issues is enough to frustrate all but the most dedicated developers. I use pre-allocated object pools for just about everything that helps, but it's easy at 60 frames a second for one allocation to build up to thousands of objects quickly if you are not very careful.
I have been working on a browser based game for TOO long now, and garbage collection is a constant problem. Plus things just run a LOT slower than a native c++ client.