It is fairly simple imperative code: you just call functions on everything.
Where it gets more complex is data and fitting that into an imperative model with very few flow control constructs: updating, creating multiple elements at once, doing weird things like calling select on elements that don't exist yet, and for most chart types there is a topological ordering on the graph of actions required to create a chart (i.e. you have to create an axis before you create a line because you need the axis that maps your data points to x,y positions)...combined with the fact that d3 throws almost no errors or misleading errors with bad inputs, and it can definitely great pretty tricky. The saving grace is the dispatcher which you can use dispatch events, and this does make it possible to break up your code.
Also, it is nothing like React. Trying to get d3 working with React is like trying to stuff a sausage through the eye of a needle. It is a great package but it is becoming a bit outdated as the world moves towards things like React. Also, for most users it is superfluous. I still use chart.js, and only move things over when I have problems.
Where it gets more complex is data and fitting that into an imperative model with very few flow control constructs: updating, creating multiple elements at once, doing weird things like calling select on elements that don't exist yet, and for most chart types there is a topological ordering on the graph of actions required to create a chart (i.e. you have to create an axis before you create a line because you need the axis that maps your data points to x,y positions)...combined with the fact that d3 throws almost no errors or misleading errors with bad inputs, and it can definitely great pretty tricky. The saving grace is the dispatcher which you can use dispatch events, and this does make it possible to break up your code.
Also, it is nothing like React. Trying to get d3 working with React is like trying to stuff a sausage through the eye of a needle. It is a great package but it is becoming a bit outdated as the world moves towards things like React. Also, for most users it is superfluous. I still use chart.js, and only move things over when I have problems.