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https://github.com/ndom91/svelte-infinite
Svelte 5 Infinite Loader using Runes
https://github.com/ndom91/svelte-infinite
infinite-loader infinite-scroll svelte svelte5
Last synced: 7 days ago
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Svelte 5 Infinite Loader using Runes
- Host: GitHub
- URL: https://github.com/ndom91/svelte-infinite
- Owner: ndom91
- License: mit
- Created: 2024-03-03T17:47:50.000Z (8 months ago)
- Default Branch: main
- Last Pushed: 2024-09-03T12:59:39.000Z (2 months ago)
- Last Synced: 2024-10-10T12:58:32.754Z (27 days ago)
- Topics: infinite-loader, infinite-scroll, svelte, svelte5
- Language: Svelte
- Homepage: https://svelte-5-infinite.vercel.app
- Size: 401 KB
- Stars: 51
- Watchers: 4
- Forks: 1
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
Svelte Infinite
[](https://npmjs.org/packages/svelte-infinite)
[](https://npmjs.org/packages/svelte-infinite)
[](https://npmjs.org/packages/svelte-infinite)
[](https://svelte-5-infinite.vercel.app)
> Svelte Infinite Loader designed and rebuilt specifically for use with **Svelte 5**
✨ Flexible
⏰ Infinite Loop Detection
📣 Control Loader State
🔎 `IntersectionObserver` based
🔥 Using Runes and Snippets
🧑🔧 **Demo**: [svelte-5-infinite.vercel.app](https://svelte-5-infinite.vercel.app)
Svelte 5 is still early days, but I couldn't find an infinite loader-type component that was maintained for the last few years of Svelte 4 even. So I had recently built this for a Svelte 5-based application I'm working on and was pretty happy with it, so I decided to share it with the world!
As Svelte 5 inevitably changes over the next weeks and months, I plan to keep this package updated and working with the latest available version of Svelte 5. Don't hesitate to open an issue if something has changed in the latest Svelte releases or you come across a bug!
## 🏗️ Getting Started
1. Install `svelte-infinite`
```bash
npm install svelte-infinite
pnpm install svelte-infinite
yarn add svelte-infinite
```
2. Import both `InfiniteLoader` and `loaderState` from `svelte-infinite`
```svelte
import { InfiniteLoader, loaderState } from "svelte-infinite"
const allItems = $state([])
const loadMore = async () => {
const res = fetch("...")
const data = await jes.json()
allItems.push(...data)
loaderState.loaded()
}
{#each allItems as user (user.id)}
{user.name}
{/each}
```
## 🍍 Example
This is a more realistic example use-case which includes a paginated data endpoint that your `triggerLoad` function should hit every time it's called to load more data. It also includes the use of some of the optional snippets to render custom markup inside the loader component.
```svelte
// +page.svelte
import { InfiniteLoader, loaderState } from "svelte-infinite"
import UserCard from "$components/UserCard.svelte"
const LOAD_LIMIT = 20
// Assume `$page.data.items` is the `+page.server.ts` server-side loaded
// and rendered initial 20 items of the list
const allItems = $state<{ id: number, body: string }[]>($page.data.items)
let pageNumber = $state(1)
// 1. This `loadMore` function is what we'll pass the InfiniteLoader component
// to its `triggerLoad` prop.
const loadMore = async () => {
try {
pageNumber += 1
const limit = String(LOAD_LIMIT)
const skip = String(LOAD_LIMIT * (pageNumber - 1))
// If there are less results on the first page (page.server loaded data)
// than the limit, don't keep trying to fetch more. We're done.
if (allItems.length < LOAD_LIMIT) {
loaderState.complete() // <--- using loaderState
return
}
const searchParams = new URLSearchParams({ limit, skip })
// Fetch an endpoint that supports server-side pagination
const dataResponse = await fetch(`/api/data?${searchParams}`)
// Ideally, like most paginated endpoints, this should return the data
// you've requested for your page, as well as the total amount of data
// available to page through
if (!dataResponse.ok) {
loaderState.error() // <--- using loaderState
// On errors, set the pageNumber back so we can retry
// that page's data on the next 'loadMore' attempt
pageNumber -= 1
return
}
const data = await dataResponse.json()
// If we've successfully received data, push it to the reactive state variable
if (data.items.length) {
allItems.push(...data.items)
}
// If there are more (or equal) number of items loaded as are totally available
// from the API, don't keep trying to fetch more. We're done.
if (allItems.length >= data.totalCount) {
loaderState.complete() // <--- using loaderState
} else {
loaderState.loaded() // <--- using loaderState
}
} catch (error) {
console.error(error)
loaderState.error() // <--- using loaderState
pageNumber -= 1
}
}
{#each allItems as user (user.id)}
{/each}
{#snippet loading()}
Loading...
{/snippet}
{#snippet error(load)}
Error fetching data
Retry
{/snippet}
```
## ♾️ Usage
This package consists of two parts, first the `InfiniteLoader` component which is a wrapper around your items. It will trigger whichever async function you've passed to the `triggerLoad` prop when the user scrolls to the bottom of the list.
Second, there is also a `loaderState` import which you should use to interact with the internal state of the loader. For example, if your `fetch` call errored, or you've reached the maximum number of items, etc. you can communicate that to the loader. The most basic usage example can be seen in the 'Getting Started' section above. A more complex example can be seen in the 'Example' section, and of course the application in `/src/routes/+page.svelte` in this repository also has a "real-world" usage example.
### `loaderState` Controller
The `loaderState` controller has 4 methods on it. You should call these at the appropriate times to control the internal state of the `InfiniteLoader`.
- `loaderState.loaded()`
- Designed to be called after a successful fetch. Will set the internal state back to `READY` so another fetch can be attempted.
- `loaderState.error()`
- Designed to be called after a failed fetch or any other error. This will cause the `InfiniteLoader` to render a "Retry" button by default, or the `error` snippet.
- `loaderState.complete()`
- Designed to be called when you've reached the end of your list and there are no more items to fetch. This will render a "No more data" string, or the `noData` snippet.
- `loaderState.reset()`
- Designed to be called when you want to reset the state of the `InfiniteLoader` to its initial state, for example if there is a search input tied to your data and the user enters a new query.
### `InfiniteLoader` Props
- `triggerLoad: () => Promise` - **required**
- The async function to call when we should attempt to load more data to show.
- `intersectionOptions: `[`IntersectionObserverInit`](https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver/IntersectionObserver#options)` = { rootMargin: "0px 0px 200px 0px" }` - optional
- The options to pass to the `IntersectionObserver` instance. See [MDN](https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver/IntersectionObserver#options) for more details. The default `rootMargin` value will cause the target to intersect 200px earlier and trigger the `loadMore` function before it actually intersects with the root element (window by default). This has the effect of beginning to load the next page of data before the user has actually reached the current bottom of the list, making the experience feel more smooth.
- If you are using a separate scroll container (element with `overflow-y: scroll`) other than the window / viewport, then it might be necessary for you to also pass a [custom `root` element](https://developer.mozilla.org/en-US/docs/Web/API/IntersectionObserver/root) here.
- `loopTimeout: number = 3000` - optional
- Length of the cool down period (in milliseconds).
- `loopDetectionTimeout: number = 2000` - optional
- The time in milliseconds in which the `loopMaxCalls` count must be hit in order to trigger a cool down period.
- `loopMaxCalls: number = 5` - optional
- The limit of `triggerLoad` executions which will trigger a cool down period, if reached within the `loopDetectionTimeout`.
### `InfiniteLoader` Snippets
Snippets [replace slots](https://svelte-5-preview.vercel.app/docs/snippets#snippets-and-slots) in Svelte 5, and as such are used here to customize the content shown at the bottom of the scroller in various states. The `InfiniteLoader` component has 5 snippet "slots" available.
- `loading`
- Shown while calling `triggerLoad` and waiting on a response.
- `noResults`
- Shown when there are no more results to display and we haven't fetched any data yet (i.e. data is less than count of items to be shown on first "page").
- `noData`
- Shown when `loaderState.complete()` is called, indicating we've fetched and displayed all available data.
- `coolingOff`
- Shown when `loaderState !== "COMPLETE"` and a loop has been detected. Will disappear and `loopTimeout` when the cooling off period expires.
- `error`
- Shown when there is an error or `loaderState.error()` has been called. The snippet has an `attemptLoad` parameter passed to it which is just the internal `triggerLoad` function, designed for a "Retry" button or similar.
## 📦 Contributing
- Initially inspired by [jonasgeiler/svelte-infinite-loading](https://github.com/jonasgeiler/svelte-infinite-loading)
- Open to contributions, issues, and feedback 🙏
## 📝 License
MIT