Learn Gluon step by step

This path assumes basic TypeScript, HTML, and npm knowledge. It does not assume framework experience. Complete the steps in order; each one adds a single new idea.

The mental model

Keep these five facts in mind:

html returns a description of DOM, called a TemplateResult.
A ref owns one reactive value. Reading .value while rendering creates the dependency; writing .value schedules the update.
Gluon updates bindings inside existing DOM when the template callsite stays the same.
A Gluon application owns effects and cleanup until unmount().
Browser standards stay visible: events are native events, Custom Elements are real Custom Elements, and styles are constructable CSSStyleSheets.

Step 1: create and run a project

npm create gluon@latest my-shop
cd my-shop
npm install
npm run dev

Open the URL printed by Vite. The generated project contains:

File	Junior-friendly purpose
`index.html`	Provides the mount element such as `<div id="app"></div>`.
`src/main.ts`	Creates state, returns the root template, and mounts the app.
`vite.config.ts`	Activates the official Gluon transform and diagnostics.
`package.json`	Lists the run, build, typecheck, and test commands.

Run npm run build before committing. A successful dev page alone does not prove that TypeScript and the production bundle are valid.

Step 2: read a template

const name = 'Orbit Lamp';
const price = 128;

html`
  <article>
    <h2>${name}</h2>
    <p>$${price}</p>
  </article>
`;

Static markup remains normal HTML. ${...} is a binding. Do not build HTML by concatenating strings; Gluon escapes ordinary values and updates the exact binding.

The most common binding forms are:

Syntax	Meaning	Example
`${value}`	Text, child template, node, or list content	`<p>${message}</p>`
`name=${value}`	String attribute	`aria-label=${label}`
`.name=${value}`	JavaScript property	`.product=${product}`
`?name=${value}`	Boolean attribute	`?disabled=${saving.value}`
`@name=${listener}`	Native event listener	`@click=${save}`

Use a property binding for objects, arrays, or live DOM properties such as input.value. Use an attribute for serializable HTML text.

Step 3: add state

import { createApp, html } from '@gluonjs/core';
import { ref } from '@gluonjs/reactivity';

const count = ref(0);

createApp(() => html`
  <button @click=${() => { count.value += 1; }}>
    Added ${count.value} time(s)
  </button>
`).mount(document.querySelector('#app')!);

The event writes the state; the template reads it. Do not call render() manually after changing a ref.

Step 4: render a stable list

Use repeat() when items have stable identities:

repeat(
  products,
  (product) => product.id,
  (product) => html`<article>${product.name}</article>`,
);

The key must be unique and stable. An array index is unsuitable when items can be reordered or removed because the index describes a position, not the item.

Step 5: own styles and cleanup

Gluon intentionally uses constructable stylesheets. A StyleSheetOwner retains only the sheets it owns and releases them during application cleanup:

const owner = createStyleSheetOwner(document);
owner.retain(css`main { max-inline-size: 40rem; }`);
app.onUnmounted(() => owner.dispose());

The full compiled feature below combines typed data, a controlled search input, derived state, a keyed list, stylesheet ownership, and page cleanup:

import {
  createApp,
  createStyleSheetOwner,
  css,
  html,
  repeat,
} from '@gluonjs/core';
import {
  computed,
  ref,
} from '@gluonjs/reactivity';

interface Product {
  readonly id: string;
  readonly name: string;
  readonly price: string;
}

const products: readonly Product[] = [
  { id: 'orbit-lamp', name: 'Orbit Lamp', price: '$128' },
  { id: 'field-tote', name: 'Field Tote', price: '$84' },
];
const query = ref('');
const visibleProducts = computed(() => {
  const needle = query.value.trim().toLowerCase();
  return needle
    ? products.filter((product) => product.name.toLowerCase().includes(needle))
    : products;
});
const styles = css`
  main { max-inline-size: 40rem; margin: 2rem auto; font: 1rem/1.5 system-ui; }
  label, article { display: grid; gap: 0.5rem; }
  section { display: grid; gap: 1rem; margin-block-start: 1.5rem; }
  article { padding: 1rem; border: 1px solid #d8d8d8; }
`;
const styleOwner = createStyleSheetOwner(document);
styleOwner.retain(styles);

const app = createApp(() => html`
  <main>
    <h1>Products</h1>
    <label>
      Search
      <input
        type="search"
        .value=${query.value}
        @input=${(event: Event) => {
          query.value = (event.currentTarget as HTMLInputElement).value;
        }}
      >
    </label>
    <p>${visibleProducts.value.length} result(s)</p>
    <section>
      ${repeat(
        visibleProducts.value,
        (product) => product.id,
        (product) => html`
          <article>
            <strong>${product.name}</strong>
            <span>${product.price}</span>
          </article>
        `,
      )}
    </section>
  </main>
`);

app.onUnmounted(() => styleOwner.dispose());
const mounted = app.mount(document.querySelector('#app')!);
window.addEventListener('pagehide', () => mounted.unmount(), { once: true });

Step 6: test public behavior

Test through the rendered surface:

import { html } from '@gluonjs/core';
import { cleanupFixtures, mountComponent } from '@gluonjs/test-utils';

const fixture = mountComponent(
  ({ label }: Readonly<{ label: string }>) => html`<button>${label}</button>`,
  { props: { label: 'Save' } },
);

if (fixture.get('button').textContent !== 'Save') throw new Error('Expected Save');
await cleanupFixtures();

Prefer queries and assertions a user or platform consumer can observe. Do not assert renderer comments, private fields, or implementation classes.

Step 7: choose the next guide

Need a reusable visual part? Continue with choosing a component level.
Need a stateful Custom Element? Continue with properties, events, and lifecycle.
Need URLs or shared state? Continue with application architecture.
Need server HTML? Continue with universal rendering.
Something failed? Read the error message and code, then open the diagnostic reference.

Common first-project mistakes

Symptom	Check
The page is empty	Confirm `index.html` has the queried mount ID and that `mount()` receives that element.
State changed but the UI did not	Read the ref as `.value` inside the app render function; do not copy it to a non-reactive variable first.
An object becomes `[object Object]`	Use `.property=${value}` rather than an attribute binding.
A checkbox or disabled control is wrong	Use `?checked=${value}` or `?disabled=${value}` for boolean attributes.
A list keeps the wrong row after removal	Give `repeat()` a stable domain key instead of the array index.
TypeScript accepts dev code but production fails	Run `npm run build`; do not rely only on the dev server.
Styles disappear or leak between surfaces	Retain constructable sheets with an explicit owner and dispose that owner.
Event code survives after navigation	Prefer template event bindings, or register imperative listeners with owner cleanup.
A component has hidden state but no lifecycle	Move the stateful boundary to `defineGluonElement()` or `GluonElement`.

Every public symbol also has a compiled, task-oriented example in the API reference. Use the Cookbook when you know the task and the API reference when you know the symbol.

Small glossary

Term	Meaning
Template	A `TemplateResult` created by `html` or `svg`.
Binding	One dynamic value inside a template.
Ref	A reactive object whose current value is `.value`.
Component	A function that returns a template, optionally with layer metadata.
Custom Element	A registered browser element with its own host and lifecycle.
Mount	Start an application in a specific container.
Unmount	Stop effects, release owned resources, and remove renderer DOM.
Quark	A thin native element or headless behavior building block.
Atom	One reusable presentational control or value.
Molecule	A small composition of related parts.
Organism	A larger reusable section or workflow boundary.