json-render-react
React renderer for json-render that turns JSON specs into React components. Use when working with @json-render/react, building React UIs from JSON, creating component catalogs, or rendering AI-generated specs.
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Install
Works with every agent the skills CLI supports.
npx skills add https://github.com/vercel-labs/json-render --skill json-render-react- 01
Install
Run the command in your project. The CLI asks which agents to install for.
- 02
Describe the task
Ask your agent for something this skill covers. It loads json-render-react automatically when relevant.
- 03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.
SKILL.md
The instructions your agent reads when the skill is triggered.
@json-render/react
React renderer that converts JSON specs into React component trees.
Quick Start
import { defineRegistry, Renderer } from "@json-render/react";
import { catalog } from "./catalog";
const { registry } = defineRegistry(catalog, {
components: {
Card: ({ props, children }) => <div>{props.title}{children}</div>,
},
});
function App({ spec }) {
return <Renderer spec={spec} registry={registry} />;
}
Creating a Catalog
import { defineCatalog } from "@json-render/core";
import { schema } from "@json-render/react/schema";
import { defineRegistry } from "@json-render/react";
import { z } from "zod";
// Create catalog with props schemas
export const catalog = defineCatalog(schema, {
components: {
Button: {
props: z.object({
label: z.string(),
variant: z.enum(["primary", "secondary"]).nullable(),
}),
description: "Clickable button",
},
Card: {
props: z.object({ title: z.string() }),
description: "Card container with title",
},
},
});
// Define component implementations with type-safe props
const { registry } = defineRegistry(catalog, {
components: {
Button: ({ props }) => (
<button className={props.variant}>{props.label}</button>
),
Card: ({ props, children }) => (
<div className="card">
<h2>{props.title}</h2>
{children}
</div>
),
},
});
Spec Structure (Element Tree)
The React schema uses an element tree format:
{
"root": {
"type": "Card",
"props": { "title": "Hello" },
"children": [
{ "type": "Button", "props": { "label": "Click me" } }
]
}
}
Visibility Conditions
Use visible on elements to show/hide based on state. New syntax: { "$state": "/path" }, { "$state": "/path", "eq": value }, { "$state": "/path", "not": true }, { "$and": [cond1, cond2] } for AND, { "$or": [cond1, cond2] } for OR. Helpers: visibility.when("/path"), visibility.unless("/path"), visibility.eq("/path", val), visibility.and(cond1, cond2), visibility.or(cond1, cond2).
Providers
| Provider | Purpose |
|---|---|
StateProvider | Share state across components (JSON Pointer paths). Accepts optional store prop for controlled mode. |
ActionProvider | Handle actions dispatched via the event system |
VisibilityProvider | Enable conditional rendering based on state |
ValidationProvider | Form field validation |
External Store (Controlled Mode)
Pass a StateStore to StateProvider (or JSONUIProvider / createRenderer) to use external state management (Redux, Zustand, XState, etc.):
import { createStateStore, type StateStore } from "@json-render/react";
const store = createStateStore({ count: 0 });
<StateProvider store={store}>{children}</StateProvider>
// Mutate from anywhere — React re-renders automatically:
store.set("/count", 1);
When store is provided, initialState and onStateChange are ignored.
Dynamic Prop Expressions
Any prop value can be a data-driven expression resolved by the renderer before components receive props:
{ "$state": "/state/key" }- reads from state model (one-way read){ "$bindState": "/path" }- two-way binding: reads from state and enables write-back. Use on the natural value prop (value, checked, pressed, etc.) of form components.{ "$bindItem": "field" }- two-way binding to a repeat item field. Use inside repeat scopes.{ "$cond": <condition>, "$then": <value>, "$else": <value> }- conditional value{ "$template": "Hello, ${/name}!" }- interpolates state values into strings{ "$computed": "fn", "args": { ... } }- calls registered functions with resolved args
{
"type": "Input",
"props": {
"value": { "$bindState": "/form/email" },
"placeholder": "Email"
}
}
Components do not use a statePath prop for two-way binding. Use { "$bindState": "/path" } on the natural value prop instead.
Components receive already-resolved props. For two-way bound props, use the useBoundProp hook with the bindings map the renderer provides.
Register $computed functions via the functions prop on JSONUIProvider or createRenderer:
<JSONUIProvider
functions={{ fullName: (args) => `${args.first} ${args.last}` }}
>
Event System
Components use emit to fire named events, or on() to get an event handle with metadata. The element's on field maps events to action bindings:
// Simple event firing
Button: ({ props, emit }) => (
<button onClick={() => emit("press")}>{props.label}</button>
),
// Event handle with metadata (e.g. preventDefault)
Link: ({ props, on }) => {
const click = on("click");
return (
<a href={props.href} onClick={(e) => {
if (click.shouldPreventDefault) e.preventDefault();
click.emit();
}}>{props.label}</a>
);
},
{
"type": "Button",
"props": { "label": "Submit" },
"on": { "press": { "action": "submit" } }
}
The EventHandle returned by on() has: emit(), shouldPreventDefault (boolean), and bound (boolean).
State Watchers
Elements can declare a watch field (top-level, sibling of type/props/children) to trigger actions when state values change:
{
"type": "Select",
"props": { "value": { "$bindState": "/form/country" }, "options": ["US", "Canada"] },
"watch": { "/form/country": { "action": "loadCities" } },
"children": []
}
Built-in Actions
The setState, pushState, removeState, and validateForm actions are built into the React schema and handled automatically by ActionProvider. They are injected into AI prompts without needing to be declared in catalog actions:
{ "action": "setState", "params": { "statePath": "/activeTab", "value": "home" } }
{ "action": "pushState", "params": { "statePath": "/items", "value": { "text": "New" } } }
{ "action": "removeState", "params": { "statePath": "/items", "index": 0 } }
{ "action": "validateForm", "params": { "statePath": "/formResult" } }
validateForm validates all registered fields and writes { valid, errors } to state.
Note: statePath in action params (e.g. setState.statePath) targets the mutation path. Two-way binding in component props uses { "$bindState": "/path" } on the value prop, not statePath.
useBoundProp
For form components that need two-way binding, use useBoundProp with the bindings map the renderer provides when a prop uses { "$bindState": "/path" } or { "$bindItem": "field" }:
import { useBoundProp } from "@json-render/react";
Input: ({ element, bindings }) => {
const [value, setValue] = useBoundProp<string>(
element.props.value,
bindings?.value
);
return (
<input
value={value ?? ""}
onChange={(e) => setValue(e.target.value)}
/>
);
},
useBoundProp(propValue, bindingPath) returns [value, setValue]. The value is the resolved prop; setValue writes back to the bound state path (no-op if not bound).
BaseComponentProps
For building reusable component libraries not tied to a specific catalog (e.g. @json-render/shadcn):
import type { BaseComponentProps } from "@json-render/react";
const Card = ({ props, children }: BaseComponentProps<{ title?: string }>) => (
<div>{props.title}{children}</div>
);
defineRegistry
defineRegistry conditionally requires the actions field only when the catalog declares actions. Catalogs with actions: {} can omit it.
Key Exports
| Export | Purpose |
|---|---|
defineRegistry | Create a type-safe component registry from a catalog |
Renderer | Render a spec using a registry |
schema | Element tree schema (includes built-in state actions: setState, pushState, removeState, validateForm) |
useStateStore | Access state context |
useStateValue | Get single value from state |
useBoundProp | Two-way binding for $bindState/$bindItem expressions |
useActions | Access actions context |
useAction | Get a single action dispatch function |
useOptionalValidation | Non-throwing variant of useValidation (returns null if no provider) |
useUIStream | Stream specs from an API endpoint |
createStateStore | Create a framework-agnostic in-memory StateStore |
StateStore | Interface for plugging in external state management |
BaseComponentProps | Catalog-agnostic base type for reusable component libraries |
EventHandle | Event handle type (emit, shouldPreventDefault, bound) |
ComponentContext | Typed component context (catalog-aware) |
FAQ
What does the json-render-react skill do?
React renderer for json-render that turns JSON specs into React components. Use when working with @json-render/react, building React UIs from JSON, creating component catalogs, or rendering AI-generated specs.
How do I install json-render-react?
Run npx skills add https://github.com/vercel-labs/json-render --skill json-render-react in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/json-render-react/ (personal) or .claude/skills/json-render-react/ (project).
Which AI agents can use json-render-react?
Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.
Is json-render-react safe to install?
No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.
Who maintains json-render-react?
It is published by vercel-labs in vercel-labs/json-render, and it is an official skill from the maker of the technology it covers. It has 391 recorded installs.
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