move old docs over

site/content/docs/03-client-api.md

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+---
+title: Client API
+---
+
+The `__sapper__/client.js` module contains functions for controlling your app and responding to events.
+
+
+### start({ target, store? })
+
+* `target` — an element to render pages to
+* `store` — an function that, given some data, returns a Store object. See the [state management](https://sapper.svelte.technology/guide#state-management) section for more detail
+
+This configures the router and starts the application — listens for clicks on `<a>` elements, interacts with the `history` API, and renders and updates your Svelte components.
+
+Returns a `Promise` that resolves when the initial page has been hydrated.
+
+```js
+import * as sapper from '../__sapper__/client.js';
+
+sapper.start({
+	target: document.querySelector('#sapper')
+}).then(() => {
+	console.log('client-side app has started');
+});
+```
+
+
+### goto(href, options?)
+
+* `href` — the page to go to
+* `options` — can include a `replaceState` property, which determines whether to use `history.pushState` (the default) or `history.replaceState`). Not required
+
+Programmatically navigates to the given `href`. If the destination is a Sapper route, Sapper will handle the navigation, otherwise the page will be reloaded with the new `href`. (In other words, the behaviour is as though the user clicked on a link with this `href`.)
+
+
+### prefetch(href)
+
+* `href` — the page to prefetch
+
+Programmatically prefetches the given page, which means a) ensuring that the code for the page is loaded, and b) calling the page's `preload` method with the appropriate options. This is the same behaviour that Sapper triggers when the user taps or mouses over an `<a>` element with [rel=prefetch](guide#prefetching).
+
+
+
+### prefetchRoutes(routes?)
+
+* `routes` — an optional array of strings representing routes to prefetch
+
+Programmatically prefetches the code for routes that haven't yet been fetched. Typically, you might call this after `sapper.start()` is complete, to speed up subsequent navigation (this is the 'L' of the [PRPL pattern](https://developers.google.com/web/fundamentals/performance/prpl-pattern/)). Omitting arguments will cause all routes to be fetched, or you can specify routes by any matching pathname such as `/about` (to match `src/routes/about.html`) or `/blog/*` (to match `src/routes/blog/[slug].html`). Unlike `prefetch`, this won't call `preload` for individual pages.