When comparing Processing.js vs Fabric.js, 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 Fabric.js is ranked 8th.
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 Out of the box Node.js support
Fabric supports node.js, and has an npm package available for server side rendering with all the dependencies handled for you. This allows you to provide graceful degradation for image fallbacks to canvas or SVG content.
Pro Vector focused API
Drawing objects in fabric are vector focused, so everything is easily transformable. It makes it easy to create complex pathed shapes, add gradients, or filters. Although fabric is great for vector rendering, it also has image support as well.
Pro Outputs to canvas and SVG and JSON
When it comes to format compatibility, Fabric is the best, with the ability to output to Canvas, SVG, and JSON. SVG provides backwards compatibility for older browsers, and JSON allows you to store rendered output for later use.
Pro Great interaction with SVG, excellent coding
If you are about to customize the library to your needs, this is the project of choice! Great programming work!
Pro Good support for SVG multi-line text
Allows creating multi-line text that can even be interactively edited by user interaction.
Pro Browser only version now available
If the node-canvas dependency is a problem you can now look for npm install fabric@x.y.z-browser
Cons
Con Processing.js is now archived, and won't be updated
Con No front-end only version via Node
NPM package has major dependencies.