Validates your JS files against JSHint on save and as you type.
apm install atom-jshint
Or Preferences > Packages > Search for
This package will run against your currently open file as you type and when you save.
I'd love for people to get involved in the development of this plugin, so please do create issues and pull requests.
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.