When comparing Processing.js vs NextCharts, 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 NextCharts is ranked 19th.
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 Great diversity
Besides having all consecrated charts like line, area, bar, horizontal bar, pie, bubble , it can have styles for line dots (solid dot, hollow dot, star, bow, anchor) or bar types (like dome, cylinder, parallelepiped). It has support for stacked bars, negative bars, combo bar-line charts, dual axis, click events and tooltips.
Pro Free
Completely free and open-source as it uses the Apache license.