Handlers

Every handler returns a Response - HTML or anything else (JSON, a redirect, 204). The routing runtime is what executes a handler.

Read handler

A GET handler with html() in its args.

html()

html() adds layouts, DOCTYPE, default cache headers, and sets the status. Skip it and a raw Response is sent as-is.

import type { ReadArgs } from "dashi";

export function Home({ html }: ReadArgs) {
  return html(
    <main>
      <h1>Hello</h1>
    </main>,
  );
}

export function getJson(): Response {
  return Response.json({ ok: true });
}

Status

Pass { status } to set the status of the html() response. Default 200.

Cache

Pass { cache } to set the Cache-Control headers. CacheStrategy picks the policy, omitted is no-store. Every sealed response sets Vary: x-slot. Public and Immutable cannot vary on Cookie or *.

Write handler

POST, PUT, PATCH, or DELETE. Call patches() or return a raw Response.

Patches

A patch is HTML aimed at an element, by #id or /path (refresh).

• update - replace the target's children
• replace - replace the target node
• append / prepend - add children
• before / after - insert siblings
• remove - drop the target
• refresh - re-fetch a RouteSlot by full src

import { patch, type WriteArgs } from "dashi";

export async function addTodo({ ctx, patches }: WriteArgs) {
  const title = (await ctx.req.formData()).get("title");
  if (typeof title !== "string") {
    return patches([]);
  }
  return patches([
    patch.append("#todos", <li>{title}</li>),
    patch.update("#count", <>3</>),
  ]);
}

Status

Pass { status } to set the status of the patches() response. Default 200.

Forms

Form submissions are the main mechanism for patches. See Forms for more details.

ctx

1. req - Request object.
2. url - URL object.
3. params - Typed params from that route. e.g. { id: string }
4. state - Partial app-defined state object. Mutate it in place. e.g. { user?: MyUser }

Middleware and errors get WrapperCtx (wide params). Layouts get LayoutCtx (state is readonly). See Layouts, middleware, errors.