From its website documentation:
app/assets will be processed by JSHint and checked for errors.
assets command as well as when the browser is refreshed during development mode. Errors are shown in the browser just like any other compilation error.
§Enablement and Configuration
JSHint processing is enabled by simply adding the plugin to your plugins.sbt file when using the
addSbtPlugin("com.typesafe.sbt" % "sbt-jshint" % "1.0.6")
The plugin’s default configuration is normally sufficient. However please refer to the plugin’s documentation for information on how it may be configured.
Next: Using RequireJs