README.md

svelte-virtual-list-ce (demo)

Community-Edition fork of svelte-virtual-list

A virtual list component for Svelte apps. Instead of rendering all your data, <VirtualList> just renders the bits that are visible, keeping your page nice and light.

Installation

yarn add svelte-virtual-list-ce

Usage

<script>
  import VirtualList from 'svelte-virtual-list-ce';

  const things = [
    // these can be any values you like
    { name: 'one', number: 1 },
    { name: 'two', number: 2 },
    { name: 'three', number: 3 },
    // ...
    { name: 'six thousand and ninety-two', number: 6092 }
  ];
</script>

<VirtualList items={things} let:item>
  <!-- this will be rendered for each currently visible item -->
  <p>{item.number}: {item.name}</p>
</VirtualList>

start and end

You can track which rows are visible at any given by binding to the start and end values:

<VirtualList items={things} bind:start bind:end>
  <p>{item.number}: {item.name}</p>
</VirtualList>

<p>showing {start}-{end} of {things.length} rows</p>

You can rename them with e.g. bind:start={a} bind:end={b}.

height

By default, the <VirtualList> component will fill the vertical space of its container. You can specify a different height by passing any CSS length:

<VirtualList height="500px" items={things} let:item>
  <p>{item.number}: {item.name}</p>
</VirtualList>

itemHeight

You can optimize initial display and scrolling when the height of items is known in advance. This should be a number representing a pixel value.

<VirtualList itemHeight={48} items={things} let:item>
  <p>{item.number}: {item.name}</p>
</VirtualList>

scrollToIndex()

You can jump to anywhere in the list, by calling scrollToIndex with one of the list items index.

<script>
  let scrollToIndex;

  function handleButtonClick (event) {
    // ... define your index variable here
    scrollToIndex(index);
  };
</script>

<VirtualList bind:scrollToIndex items={things}>
  <p>{item.number}: {item.name}</p>
</VirtualList>

You can also export let scrollToIndex to call it from outside. In this case it should be initialized with undefined, to prevent warnings in the logs:

<!-- InnerComponent.svelte -->
<script>
  export let scrollToIndex = undefined;
</script>

<!-- OuterComponent.svelte -->
<script>
  let scrollToIndex;
  function someLogic () {
    scrollToIndex(index);
  };
</script>

<InnerComponent bind:scrollToIndex></InnerComponent>

Configuring webpack

If you're using webpack with svelte-loader, make sure that you add "svelte" to resolve.mainFields in your webpack config. This ensures that webpack imports the uncompiled component (src/index.html) rather than the compiled version (index.mjs) — this is more efficient.

If you're using Rollup with rollup-plugin-svelte, this will happen automatically.

License

LIL