API reference

`useContent()`

The useContent() function retrieves the nearest content information for the current route. The returned object includes:

headings: ContentHeading[] | undefined;
menu: ContentMenu | undefined;

The headings array includes data about a markdown file's <h1> to <h6> html heading elements.

Menus are contextual data declared with menu.md files. See menus file definition for more information on the file format and location.

`useDocumentHead()`

Use the useDocumentHead() function to retrieve the document head metadata.

useDocumentHead() retrieves a DocumentHead object that will allow you to:

update the title in <head>.
update the meta tags in <head>.
update the link tags in <head>.
update the style tags in <head>.

The useDocumentHead() function can be used within a Qwik component, such as <RouterHead>, to create the inner elements within document.head.

import { component$ } from '@builder.io/qwik';
import { useDocumentHead } from '@builder.io/qwik-city';

/**
 * The RouterHead component is placed inside of the document `<head>` element.
 */
export const RouterHead = component$(() => {
  const head = useDocumentHead();

  return (
    <>
      <title>{head.title}</title>

      <meta name="viewport" content="width=device-width, initial-scale=1.0" />
      <link rel="icon" type="image/svg+xml" href="/favicon.svg" />

      {head.meta.map((m) => (
        <meta {...m} />
      ))}

      {head.links.map((l) => (
        <link {...l} />
      ))}

      {head.styles.map((s) => (
        <style {...s.props} dangerouslySetInnerHTML={s.style} />
      ))}
    </>
  );
});

`useLocation()`

Use the useLocation() function to retrieve a RouteLocation object for the current location.

export interface RouteLocation {
  readonly params: RouteParams; // Record<string,string>
  readonly href: string;
  readonly pathname: string;
  readonly query: Record<string, string>;
  readonly isNavigating: boolean;
  readonly url: URL;
}

The return value of useLocation() is similar to document.location, but it is safe to use on the server where there is no global location object.

Path Route Parameters

useLocation() encodes the Route Parameters as params.

Assume you have:

Route: https://example.com/sku/[skuId]
User navigates to: https://example.com/sku/1234
Then the skuId can be retrieved through useLocation().params.skuId.

import { component$ } from '@builder.io/qwik';
import { useLocation } from '@builder.io/qwik-city';

export default component$(() => {
  const loc = useLocation();

  return (
    <>
      <h1>SKU</h1>
      <p>pathname: {loc.url.pathname}</p>
      <p>skuId: {loc.params.skuId}</p>
    </>
  );
});

The above code would generate:

<h1>SKU</h1>
<p>pathname: /sku/1234</p>
<p>skuId: 1234</p>

Notice that useLocation is a read-only API, you should never attempt to mutate the values of the loc object returned. Instead look into the useNavigate() API.

`useNavigate()`

The useNavigate() function allows to programatically navigate to the next page without involving a user click or causing a full-page reload. This is the API used by the <Link> component internally to support SPA navigation.

This function returns a goto() function that can be used to navigate to a new path.

import { component$ } from '@builder.io/qwik';
import { useNavigate } from '@builder.io/qwik-city';

export default component$(() => {
  const nav = useNavigate();

  return (
    <>
      <button
        onClick$={() => {
          // this assigment causes SPA navigation
          nav('/dashboard');
        }}
      >
        Go to dashboard
      </button>

      <button
        onClick$={() => {
          // call without arguments to refresh the current page
          nav();
        }}
      >
        Refresh page
      </button>
    </>
  );
});

This component will have a button then when clicked, QwikCity will navigate to /dashboard without causing a page reload.

Notice that for SEO, and accesibility it's better to use the <Link> component instead of useNavigate() programatically to navigate to a new page after some user interaction.

`loader$()`

The loader$() function is used to declare a new Server Loader in the given page/endpoint or layout. QwikCity will execute all the declared loaders for the given route match. Qwik Components can later reference the loaders, by importing them and calling the .use() method in order to retrieve the data.

import { component$ } from '@builder.io/qwik';
import { loader$ } from '@builder.io/qwik-city';

export const useGetTime = loader$(() => {
  return { time: new Date() }
});
export default component$(() => {
  const signal = useGetTime(); // Signal<{time: Date}>
  console.log('Date': signal.value.time);
  return (
    <div>{signal.value.time.toISOString()}</div>
  )
});

Please refer to the Server Loaders section for more information.

`action$()`

The action$() function is used to declare a new Server Action in the given page/endpoint or layout. QwikCity will execute only the invoked action after some user interaction (such as a button click or a form submit).

Please refer to the Server Actions section for more information.

`<QwikCityProvider>`

The QwikCityProvider component initializes QwikCity in the existing document, providing the necessary context for QwikCity to work, such as useContent() and useLocation().

This component is usually located at the very root of your application, in most of the starters you will find it in the src/root.tsx file:

import { QwikCityProvider, RouterOutlet } from '@builder.io/qwik-city';

export default function Root() {
  return (
    <QwikCityProvider>
      <head>
        <meta charSet="utf-8" />
      </head>
      <body>
        <RouterOutlet />
      </body>
    </QwikCityProvider>
  );
}

QwikCityProvider does not render any DOM element, not even the matched route, it merely initializes QwikCity core logic, because of this reason, it should not be used more than once in the same app.

`<RouterOutlet>`

This component is the responsable for rendering the matched route at a given moment, it used internally the useContent() and to render the current page, as well as all the nested layouts.

This component is usually located as a child of <body>, in most of the starters you will find it in the src/root.tsx file:

`<Form>`

The Form component is a wrapper around the native <form> element, and it's designed to work side by side with Server Actions.

Since this component uses the native <form> element, it will work with any browser with and without JavaScript enabled, in addition, it enhances the native <form> element by captuing the submit event and preventing the default behaviour, so it will behave like a SPA (Single Page Navigation) instead of a full page reload.

import { component$ } from '@builder.io/qwik';
import { Form, action$ } from '@builder.io/qwik-city';

// this action will be called when the form is submitted
export const useLoginAction = action$((data, { cookies, redirect }) => {
  if (validate(data.username, data.password)) {
    cookies.set('auth', getAuthToken(data.username));
    throw redirect(302, '/dashboard');
  }
});

export default component$(() => {
  const login = useLoginAction();

  return (
    <Form action={login}>
      <input type="text" name="username" />
      <input type="password" name="password" />
      <button type="submit">Login</button>
    </Form>
  );
});

`<Link>`

The Link component works like the <a> anchor element, but instead of causing a full page reload, it will navigate as a SPA (Single Page Navigation). This is useful if you need to navigate without losing current state.

Notice that full-page reloads in Qwik are extremely cheap, other frameworks abuse SPA links because, a full page reload requires JS to hydrate and reexecute everything. This is not the case for Qwik. We found in our internal testing that using <a> usually leads to the most snappy interactions.

Under the hood, the <Link> component uses the useNavigate() API and prevents the default behaviour of the native <a>:

import { component$ } from '@builder.io/qwik';
import { useNavigate } from '@builder.io/qwik-city';

export const Link = component$<LinkProps>((props) => {
  const nav = useNavigate();

  return (
    <a
      preventdefault:click
      onClick$={() => {
        nav(props.href);
      }}
      {...props}
    >
      <Slot />
    </a>
  );
});

Usage

import { component$ } from '@builder.io/qwik';
import { Link } from '@builder.io/qwik-city';

export default component$(() => {
  return (
    <div>
      <a href="/docs" class="my-link">
        full-page reload
      </a>
      <Link href="/docs" class="my-link">
        spa navigation
      </Link>
    </div>
  );
});