ComfyUI/web/extensions/core/subflow.js

import { app } from "../../scripts/app.js";
import { api } from "../../scripts/api.js";

app.registerExtension({
  name: "Comfy.Subflow",
  async nodeCreated(node) {

    if (!node.widgets) return;
    if (node.widgets[0].name !== "subflow_name") return;

    let outputSlots = []; // (int (node), int (slot))
    let inputSlots = [];

    const refreshPins = async (subflowName) => {
      const subflowData = await api.getSubflow(subflowName);
      if (!subflowData.subflow) return;

      inputSlots = [];
      outputSlots = [];

      const subflowNodes = subflowData.subflow.nodes
      updateSubflowPrompt(subflowData.subflow);
      // remove all existing pins
      const numInputs = node.inputs?.length ?? 0;
      const numOutputs = node.outputs?.length ?? 0;
      for(let i = numInputs-1; i > -1; i--) {
        node.removeInput(i);
      }
      for(let i = numOutputs-1; i > -1; i--) {
        node.removeOutput(i);
      }

      for (const subflowNode of subflowNodes) {
        const exports = subflowNode.properties.exports;
        if (exports) {
          let pinNum = 0;
          for (const inputRef of exports.inputs) {
            const input = subflowNode.inputs.find(q => q.name === inputRef);
            if (!input) continue;
            node.addInput(input.name, input.type);
            inputSlots.push([subflowNode.id, pinNum]);
            pinNum++;
          }
          pinNum = 0;
          for (const outputRef of exports.outputs) {
            const output = subflowNode.outputs.find(q => q.name === outputRef);
            if (!output) continue;
            node.addOutput(output.name, output.type);
            outputSlots.push([subflowNode.id, pinNum]);
            pinNum++;
          }
        }
      }
    };

    const updateSubflowPrompt = (subflow) => {
      node.subflow = subflow;
    };

    // node.onSerialize = () =>
    node.onConfigure = () => refreshPins(node.widgets[0].value);
    node.widgets[0].callback = (subflowName) => refreshPins(subflowName);

    node.getExportedOutput = (slot) => {
      return outputSlots[slot];
    };

    node.getExportedInput = (slot) => {
      return inputSlots[slot];
    };

  }
});