title: c3.js - Execute only after c3 has generated data
body: <p>I am generating c3 charts, during the time it is painting the charts, I need to show a waiting icon.</p>
  
  <p>Presently, the icon is implemented with some random timeout due to which the waiting icon disappears, and c3 charts is still not rendered.</p>
  
  <p>I want to keep that waiting icon spinning, and should disappear only after the c3 charts have been rendered. Not sure how to do it.</p>