When comparing GSAP vs D3.js, the Slant community recommends GSAP for most people. In the question“What are the best JavaScript animation frameworks or libraries?” GSAP is ranked 1st while D3.js is ranked 2nd. The most important reason people chose GSAP is:
It's been around a long time, from back in Flash days.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Mature
It's been around a long time, from back in Flash days.
Pro Fast
It has always stressed performance.
Pro Lightweight
It's always stressed file size. There are different versions available to balance features and weight.
Pro Large community
D3.js is a very popular tool with an active community, resulting in plenty of learning resources and fast responses to questions.
Pro Huge number of examples online
Most of the examples provided are by the author, but there's also a great community writing plugins and more examples.
Pro Doesn't require a proprietary framework
D3's emphasis on web standards gives you the full capabilities of modern browsers without tying yourself to a proprietary framework.
Pro Versatile library for manipulating data on the DOM
Pro Very flexible join paradigm
Can be tricky at first, but once learned, data manipulation and binding can easily generate complex visualizations for massive amounts of data.
Pro Great for highly interactive scenes
D3.js offers incredible levels of interactivity.
Pro Backwards compatible
D3.js is intended for modern browsers, so supports IE9 and above (IE8 with an additional library) as well as all the other modern browsers.
Cons
Con Steep learning curve
The complexity and flexibility of D3.js results in it being a time-consuming tool to learn for many users.
D3 is incredibly flexible; probably more so than any other JavaScript visualization library at the time of this posting. With that flexibility comes increased complexity. If you just want to create some quick charts you will get results faster with something else.
Con "Selections" are elegant, but somewhat hard to grok
Selections are core to working with D3 beyond the basics. They're powerful and useful, but require new developers to get up to speed (e.g. set aside 30m to read and digest: https://github.com/mbostock/d3/wiki/Selections) and if used in the context of a larger application will result in a portion of the code using different patterns than the rest, requiring a translation layer in between.