Dualside physics engine for JS

[ZackMercury]

We're working on a 2-dimensional game, that requires some physics, so the best solution we've figured out to do is to make both serverside physics calculation and clientside physics calculation and just check for desyncs every 1000ms. First we've tried to apply separating axis theorem, but it actually doesn't solve physics. The problem is that our shapes will not be regular, they can be custom, and we need to write more advanced stuff like bouncing of a ball against any side of our custom shape(or composite shape), so we decided to use some engine that will solve our physics problem. 

I've been searching for an engine that won't have much desynchronizations with clientside code and Node.JS. Maybe anyone can give us some direction or advice?

[Fricken Hamster]

If the physics is such an integral part of the gameplay, you might want to look into a lockstep networking method, like that old age of empires article.