Cytoscape v4 -- planning for breaking API changes

Brainstorming of improvements that would cause breaking changes for a potential, future v4:

Modernising:

• Add support for ESM bundles referenced by package.json. This breaks support for CJS code that is bundled by Webpack. See also exports (e.g. is-promise).
• Remove internal polyfills. If you want to support old browsers that are missing these objects, use a polyfill like core-js. Note which objects in the stdlib need polyfilling: Promise, Set, Map, etc.
• Use browser-friendly module links #2661
• Use Rust/WASM for increased performance (e.g. threading) #2799
• Use WebGL #2798

Improving formatting & naming:

• ele.json() returns classes as an array
• Make percent values be specified on [0, 1] when no units are specified, e.g. 0.5 is the same as 50%. In v3, if you specify 0.5, you will get 0.5%.
• Make the { nodes: [], edges: [] } elements JSON format no longer the default for cy.json() export. Instead use, the plain array format.
• Rename the core selector to cy, by default. The core value should still work, but it won’t be returned by cy.json().

Removing deprecated features & other mistakes:

• Remove cy.forceRender(). Deprecated long ago.
• Remove ele.renderedStyle() (Deprecated in #2223)
• Remove cy.batchData(). Deprecated long ago.
• Don’t set concentric scratch values when running the concentric layout. The programmer can store values himself.
• Remove support for event namespaces. It’s not all that useful and it adds complexity.
• Remove non-JSON style formats and revise cy.style() to only be a JSON setter. Ref: https://github.com/cytoscape/cytoscape.js/issues/2637#issuecomment-600734097
• Remove width: label and height: label. Ref. #2713

Moving features to external extensions or libraries:

• Remove cose from the core bundle and make it an external extension. The force-directed layout that a programmer should choose by default is fcose.
• Remove selectionType: 'additive' from the core lib and turn it into an extension
• Remove pie chart properties. You can just use a library like Chart.js or C3 to generate charts as background images.

Removing features that are problematic for performance:

• Remove array-like indexing support, e.g. eles[0]. You would need to call eles.at(0) instead.
• Traversal selectors are expensive. They create additional expense every time any element gets modified. It would be better for performance for a consumer to use classes. The consumer can add or remove classes based on the graph topology, and he can do so more precisely than with a declarative selector.
  • Remove edge operators in selectors (e.g. node -> node).
  • Remove compound traversal selectors (e.g. node.parent > node.child). You can still use :parent or :child to generally style parent nodes and child nodes.

[StevenLangbroek]

Since a class is a concept in Javascript now, maybe it’s better to use classNames? Ecosystem seems to be standardising on this.

[maxkfranz]

This issue is for discussing v4 API – i.e. breaking API changes. If you have a general feature in mind that is additive w.r.t. API, then feel free to make an ordinary feature request and the corresponding pull request.