nl_tokens: ( arg → string classId → string callback → function ) - register inView handler
pl_tokens: function ( arg , classId , callback ) { var view = inView ( '.' + classId ) arg === 'on' ? view . on ( 'enter' , callback . enter ) . on ( 'exit' , callback . exit ) : arg === 'once' ? <mask> . once ( 'enter' , callback . enter ) . once ( 'exit' , callback . exit ) : console . warn ( '[in-view] event handler not found' ) }