How do I interpret the __transition__ property that D3 attaches to DOM elements as part of a transition?

Question

I implemented a chained transition using the transition.transition() pattern ( https://github.com/mbostock/d3/wiki/Transitions#transition ).

The __transition__ property after the first transition is scheduled:

{"4":{"tween":{},"time":1410878734661,"delay":0,"duration":1500},"active":0,"count":1}

The __transition__ property after the second transition is scheduled:

{"4":{"tween":{},"time":1410878734661,"delay":0,"duration":1500},"5":{"tween":{},"time":1410878734661,"delay":1500,"duration":500},"active":0,"count":2} 

Is "4" the id associated with both parts of this chained transition? Does active:0 indicate there are no actively running transitions? Does the count property indicate the number of transitions scheduled?

Thanks in advance!

var t0 = text.transition().delay(0).duration(1500) //first transition
var t1 = t0.transition().ease("bounce").duration(500) //second transition

Answer 1

The numbers in your object are indeed the ID of the transitions. active holds the ID of the active transition and count the total number of transitions.

More information in the source .