Quick Start

Render a JSON spec as a live Angular component tree in 5 minutes.

Prerequisites

Angular 20+ project with @threadplane/render installed. See the Installation guide if you need setup help.

Create a component to render

Let's start with a simple Angular component for the spec to render. Every rendered component receives inputs matching the AngularComponentInputs interface -- your custom props are spread alongside the standard inputs.

// text.component.ts
import { Component, ChangeDetectionStrategy, input } from '@angular/core';
import type { Spec } from '@json-render/core';
 
@Component({
  selector: 'app-text',
  standalone: true,
  changeDetection: ChangeDetectionStrategy.OnPush,
  template: `<p>{{ label() }}</p>`,
})
export class TextComponent {
  readonly label = input<string>('');
  readonly childKeys = input<string[]>([]);
  readonly spec = input.required<Spec>();
}

Define a registry

Map element type names to Angular component classes using defineAngularRegistry().

// ui-registry.ts
import { defineAngularRegistry } from '@threadplane/render';
import { TextComponent } from './text.component';
 
export const uiRegistry = defineAngularRegistry({
  Text: TextComponent,
});

Build a spec

Now let's describe the UI tree itself. A spec is a flat map of elements, and the root key points to the entry element.

// app.component.ts
import { Component, ChangeDetectionStrategy } from '@angular/core';
import { RenderSpecComponent } from '@threadplane/render';
import type { Spec } from '@json-render/core';
import { uiRegistry } from './ui-registry';
 
@Component({
  selector: 'app-root',
  standalone: true,
  imports: [RenderSpecComponent],
  changeDetection: ChangeDetectionStrategy.OnPush,
  template: `
    <render-spec [spec]="spec" [registry]="registry" />
  `,
})
export class AppComponent {
  registry = uiRegistry;
 
  spec: Spec = {
    root: 'greeting',
    elements: {
      greeting: {
        type: 'Text',
        props: { label: 'Hello from @threadplane/render!' },
      },
    },
  };
}

Run your app

ng serve

Open http://localhost:4200. You should see "Hello from @threadplane/render!" rendered by your TextComponent.

Adding Reactive State

Specs get a lot more interesting once you connect them to a state store. Props with $state expressions read from the store reactively.

import { Component, ChangeDetectionStrategy } from '@angular/core';
import { RenderSpecComponent, signalStateStore } from '@threadplane/render';
import type { Spec } from '@json-render/core';
import { uiRegistry } from './ui-registry';
 
@Component({
  selector: 'app-root',
  standalone: true,
  imports: [RenderSpecComponent],
  changeDetection: ChangeDetectionStrategy.OnPush,
  template: `
    <render-spec [spec]="spec" [registry]="registry" [store]="store" />
    <button (click)="updateName()">Change Name</button>
  `,
})
export class AppComponent {
  registry = uiRegistry;
  store = signalStateStore({ name: 'World' });
 
  spec: Spec = {
    root: 'greeting',
    elements: {
      greeting: {
        type: 'Text',
        props: { label: { $state: '/name' } },
      },
    },
  };
 
  updateName() {
    this.store.set('/name', 'Angular');
  }
}

Clicking the button updates the store, which reactively updates the rendered TextComponent label from "World" to "Angular".

Using Spec-Embedded State

You can also embed initial state right in the spec. When you don't pass an external store, RenderSpecComponent creates an internal signalStateStore from spec.state for you:

spec: Spec = {
  root: 'greeting',
  elements: {
    greeting: {
      type: 'Text',
      props: { label: { $state: '/message' } },
    },
  },
  state: {
    message: 'State embedded in the spec!',
  },
};

<!-- No [store] input needed -- an internal store is created from spec.state -->
<render-spec [spec]="spec" [registry]="registry" />

Next Steps

Spec format, conditional rendering, and repeat loops

State Store Guide

→

Reactive state management with signalStateStore()

Events Guide

→

Event handlers and action dispatch