Node Categories

Every node type belongs to exactly one of 9 categories. A node's category determines its header color/icon on the canvas and which group it appears under in the node picker — this is also how the Node Reference is organized.

Category	Color	What it's for
Server	slate	Creating and starting the Express app (express.init, express.listen).
Routing	blue	Defining HTTP routes (express.route).
Middleware	amber	Request-processing middleware, built-in or custom (app.use(...)).
Handler	emerald	Terminal request handlers — the end of a route's chain.
Operators	cyan	Pure, value-producing arithmetic/comparison/boolean nodes — no execution pins.
Control Flow	lime	Directing execution: Branch (if/else), Switch, and Sequence (run every wired output, in order).
Logic	violet	Functions, variables, requiring modules, property-path extraction, and module-load-time setup.
Array	light grey	Array iteration (map, filter, reduce, etc. with wireable loop bodies), simple methods (push, pop, includes, etc.), and the Is Array check.
Object	indigo	Working with plain objects: Object Assign (merge objects).
Error	red	Handling thrown errors: Try Catch and Throw.
Debugging	rose	Console Log.

This is the exact order the Node Reference presents them in, and the same order/colors you'll see in the editor's own category legend and node picker.

Availability: main canvas vs. Function Graphs

A Function node can be authored either as hand-typed code or as its own nested visual node graph ("blueprint mode" — see Function Graphs & Blueprint Mode). Not every node type is available in both places:

• Main canvas only: express.init, express.listen, express.middleware.jsonParser, middleware.customCode, express.route, logic.handlerFunction, logic.function, logic.export, logic.require, logic.begin.
• Function Graph only: logic.graphEntry (the graph's entry point, never added manually — managed via the Function Graph editor's own panel). logic.graphReturn (Return) is no longer Function-Graph-only — it's also usable directly inside an array.* loop body on the main canvas.
• Both, full parity: logic.functionCall, logic.callback, logic.pathExtractor, logic.promise, logic.graphReturn, variable.get, variable.set, debug.consoleLog, handler.sendJson, all 17 operators.* nodes, all three controlFlow.* nodes (branch, switch, sequence), all 16 array.* nodes (including array.isArray), object.assign, and both error.* nodes (tryCatch, throw).

One further exception: logic.promise can also be nested inside ANOTHER Promise node's own Blueprint executor graph, to any depth — the only node type addable inside a nested Blueprint sub-canvas besides the types already listed above for "Both, full parity".

Each node's page in the Node Reference notes which of these applies.