When comparing Mastering data visualization with D3.js - Adam Janes (Udemy) vs D3 Gallery, the Slant community recommends D3 Gallery for most people. In the question“What are the best resources to learn D3.js?” D3 Gallery is ranked 5th while Mastering data visualization with D3.js - Adam Janes (Udemy) is ranked 8th. The most important reason people chose D3 Gallery is:
The gallery is [updated frequently](https://github.com/mbostock/d3/wiki/Gallery/_history) with improvements and new examples.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Updated often
The gallery is updated frequently with improvements and new examples.
Pro A lot of visual appealing examples including source code
There are hundreds of examples to look at, including the source code. This will give you a great idea of what D3.js is capable of.
Cons
Con Examples only
The D3 gallery isn't a tutorial, it only shows examples of graphs created with D3.
For someone completely new to D3, this would likely be an overwhelming place to start.