chained-transitions.js

function expandShrink(){
  d3.select("#blueCircle")
    .transition()
    .duration(1600)
    .attr("r", 50)    // increase radius to 50px
      .transition()
      .duration(800)
      .attr("fill", "yellow")   // change to yellow (why not!)
        .transition()
        .duration(800)
        .attr("r", 20)            // shrink radius back to 20px
        .attr("fill","lightblue") // change back to blue
}