Most of the [examples](https://github.com/mbostock/d3/wiki/Gallery) provided are by the author, but there's also a great community writing plugins and more examples.
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Pergola runs seamlessly in an HTML environment (option in configuration file). All the examples are provided both as SVG standalone and embedded in HTML, and are strictly equal.
Besides its universal Node Helper (http://www.svgmagazine.com/jul2011/dom-helper.html) Pergola also provides the equivalent for building HTML nodes and <foreignObject> HTML nodes.
Pro SVG native
The first and most accomplished SVG native library, 100% cross-platform compatible.
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 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 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.
Con Commercial license
PERGOLA does not offer a free version. The price for a single developer to use PERGOLA is 400 €.
Con Steep learning curve
The complexity and flexibility of D3.js results in it being a time-consuming tool to learn for many users.
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.