[jamra]

D3 gives you a diff algorithm for free. That handles adding new items to your visualization, updating existing ones, and removing them. You implement the enter, exit, and update (update may have been deprecated). That makes it easy to take your data and handle changes. It will handle animations in a very easy way for each of those cases as well.

In data visualization, creating a scale based on the domain of your data (the range of your data) is annoying. This is handled for you by utility libraries in d3. It also can draw the line ticks of the scale without issues.

Also placing labels is not too easy. D3 does that nicely.

The truth is you can do all of that yourself, but if I were to try it, I would go over the d3 utilities first just to see how complicated some of the visual aspects you haven’t thought of but will need are.

The drawing part of d3 (SVG, canvas) are not so hard to do on your own, but the way d3 isolates the context of what you are coding is very helpful. I’ve only run through the examples and read the d3 book as well as several other charting books, but I don’t use d3 on a day to day.

But let’s go over a more realistic example. In one of my books, the author writes about simple line charts and displaying the quartiles (made by standard deviations) of the data. None of my charting libraries handle that. Rolling my own would be very time consuming. Doing this in d3 would be more feasible than the alernatives.