When comparing Processing.js vs PERGOLA, the Slant community recommends Processing.js for most people. In the question“What are the best JavaScript drawing libraries?” Processing.js is ranked 4th while PERGOLA is ranked 25th.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Good at creating complex visual effects and filters
Pro Fast rendering of complex scenes
Because Processing doesn't keep track of shape objects it's more efficient than other libraries. Processing can do more complicated effects faster than other libraries. Although this means you have to keep track of more yourself in your code, it also means you have more control over the finer details of how things are rendered.
Pro Cross-platform compatibility
In processing you can write code in both JavaScript and Processing code. This allows you to use existing Processing code on the client side.
Processing code is similar to Java in that it has static typing. This can make more complex calculations more robust, and less likely to cause conflicts.
The library takes a more frame based approach to rendering, so you use drawing functions to draw directly to the frame without objects. This can make it easier to write efficient full frame rendering scenes and post processing effects.
Pro HTML
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.
Cons
Con Processing.js is now archived, and won't be updated
Con Commercial license
PERGOLA does not offer a free version. The price for a single developer to use PERGOLA is 400 €.