comfyui-node-frontend

ComfyUI Frontend Extensions

Custom nodes can extend the ComfyUI frontend with JavaScript. Extensions register hooks, widgets, commands, settings, and UI components.

Quick Start

1. Export WEB_DIRECTORY in Python

# __init__.py
WEB_DIRECTORY = "./js"
__all__ = ["WEB_DIRECTORY"]

2. Create JavaScript Extension

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

app.registerExtension({
    name: "my_nodes.my_extension",

    async setup() {
        console.log("Extension loaded!");
    },
});

All .js files in WEB_DIRECTORY are loaded automatically when ComfyUI starts.

Extension Hooks (Lifecycle Order)

init — After canvas created, before nodes

app.registerExtension({
    name: "my.ext",
    async init(app) {
        // Modify core behavior, add global listeners
    },
});

addCustomNodeDefs — Modify node definitions

async addCustomNodeDefs(defs, app) {
    // defs is a dict of all node definitions
    // Can add or modify definitions before registration
    defs["MyFrontendNode"] = {
        input: { required: { text: ["STRING", {}] } },
        output: ["STRING"],
        output_name: ["text"],
        name: "MyFrontendNode",
        display_name: "My Frontend Node",
        category: "custom",
    };
},

getCustomWidgets — Register custom widget types

getCustomWidgets(app) {
    return {
        MY_WIDGET(node, inputName, inputData, app) {
            const widget = node.addWidget("text", inputName, "", () => {});
            widget.serializeValue = () => widget.value;
            return { widget };  // or { widget, minWidth, minHeight }; v1.54+ also accepts `return widget`
        },
    };
},

beforeRegisterNodeDef — Modify node prototype

async beforeRegisterNodeDef(nodeType, nodeData, app) {
    if (nodeData.name === "MyNode") {
        // Chain onto prototype methods
        const origOnCreated = nodeType.prototype.onNodeCreated;
        nodeType.prototype.onNodeCreated = function () {
            origOnCreated?.apply(this, arguments);
            // Add custom widget, modify behavior, etc.
            this.addWidget("button", "Run", null, () => {
                console.log("Button clicked!");
            });
        };
    }
},