Yep. There is no point at all knowing anything that is presented here without understanding how the API actually works from a high level. For me it was an "aha" moment when suddenly everything made sense (and I realised how nice d3 actually is).
The other big problem with d3 is that you don't get much for free with it. Many people are surprised that you have to draw a bar chart using rectangles. But d3 doesn't "draw graphs", it just maps values from your data into attributes in the DOM. You have to know HTML, SVG, CSS, and, of course, Javascript very well already to have any success with d3.
The other big problem with d3 is that you don't get much for free with it. Many people are surprised that you have to draw a bar chart using rectangles. But d3 doesn't "draw graphs", it just maps values from your data into attributes in the DOM. You have to know HTML, SVG, CSS, and, of course, Javascript very well already to have any success with d3.