Develop mode in grafana 3.x

I guess if there is a solution in grafana 3.x that we can develop with real-time change. I mean like npm run dev. Anyone know, please tell me.

Here is the guide for how to build grafana (if you git clone Grafana master repo):

If you have running Grafana 3.x and want to make a modification you need to git clone a old v3.x branch and look at an old building from source guide to try to build that old branch.