How about StackEdit: https://stackedit.io/ Source: https://github.com/benweet/stackedit/
--Edit--
Looks like StakEdit is an application not an implementation. You could look into PageDown https://code.google.com/p/pagedown/ which StackEdit is built on. Since you are looking for editors specifically for AngularJS (which I missed on the first read through :) ) here are some examples: https://github.com/programmieraffe/angular-editors However it looks like none of them implement the math/latex formulas that is something that StackEdit added for their implementation.