@dathra/runtime

Low-level DOM runtime for Dathra. Handles CSR (client-side rendering), SSR (server-side rendering), and hydration through separate entry points.

Install

npm install @dathra/runtime

Entry Points

CSR API

import {
  fromTree,
  firstChild,
  nextSibling,
  setText,
  setAttr,
  setProp,
  spread,
  append,
  insert,
  event,
  reconcile,
} from "@dathra/runtime";
import { templateEffect, createRoot, onCleanup } from "@dathra/reactivity";

fromTree(tree, ns)

Create a DOM factory from a structured array (Tree). Returns () => DocumentFragment.

const factory = fromTree([["div", { class: "app" }, "Hello"]], 0);
const fragment = factory(); // DocumentFragment with <div class="app">Hello</div>

firstChild(node, skipText?) / nextSibling(node, skipText?)

Navigate the DOM tree. Used by compiled output to locate dynamic nodes.

const div = firstChild(fragment);
const text = firstChild(div, true); // skip to first non-text child
const next = nextSibling(text);

setText(node, value)

Set a text node's content.

templateEffect(() => setText(textNode, count.value));

setAttr(el, key, value) / setProp(el, key, value)

Set an HTML attribute or DOM property.

setAttr(el, "class", "active");
setProp(el, "checked", true);

spread(el, props)

Spread an object of props onto an element, diffing against previous values.

spread(el, { class: "btn", onClick: handler });

append(parent, child) / insert(parent, child, anchor)

DOM insertion primitives.

append(container, fragment);
insert(container, newNode, referenceNode);

event(type, el, handler)

Attach a DOM event listener.

event("click", button, () => count.update((n) => n + 1));

reconcile(parent, items, keyFn, createFn, updateFn?)

Keyed list reconciliation for efficient list rendering.

templateEffect(() => {
  reconcile(
    listEl,
    items.value,
    (item) => item.id,
    (item) => {
      const el = document.createElement("li");
      el.textContent = item.name;
      return el;
    },
  );
});

SSR API

import {
  renderToString,
  renderTree,
  serializeState,
  createMarker,
  MarkerType,
} from "@dathra/runtime/ssr";

renderToString(tree, state, dynamicValues)

Render a structured array tree to an HTML string with SSR markers.

renderTree(tree, options)

Lower-level tree rendering with custom options.

serializeState(state)

Serialize component state for transfer to the client using devalue.

createMarker(type, id?)

Create SSR marker comments for hydration boundaries.

Hydration API

import {
  hydrate,
  hydrateRoot,
  createHydrationContext,
  isHydrated,
} from "@dathra/runtime/hydration";

hydrate(shadowRoot, setup)

Hydrate a Shadow DOM root, attaching reactivity to existing SSR-rendered DOM.

hydrateRoot(root)

Hydrate a regular DOM root.

createHydrationContext()

Create a hydration context for walker-based marker resolution.

isHydrated(root)

Check if a root has already been hydrated (idempotency guard).

Bundle Size

• CSR core: ~1.8 KB gzip
• SSR / Hydration: loaded separately, tree-shakable

License

MPL-2.0