This sample builds up on ch03e04 Watch Task, by breaking down watch into many targets, one for each build task that can be affected by file changes.

If you run grunt dev this time, and then change some files, you'll see that watch will be smart enough about it to run only the build task(s) affected by the changed files, rather than the entire build process. This is the preferred approach because it saves time and gives you a finer-grained control, by avoiding to run tasks unnecessarily, when we know their output will stay the same.

grunt dev

Then change a file, sit back, and enjoy.

P.S: If the Gruntfile.js, or any build related files change, altering the process itself, then by all means, run a full build again!