Super tiny, simple to use SvelteJS store for real-time updates from server via SSE.

Install

npm i svelte-streamable --save-dev

yarn add svelte-streamable

CDN: UNPKG | jsDelivr (available as window.Streamable)

If you are not using ES6, instead of importing add

<script src="/path/to/svelte-streamable/index.js"></script>

just before closing body tag.

Usage

Store for any server updates in JSON format

Just provide Server-sent event endpoint as url property in config object.

import { streamable } from 'svelte-streamable';

const updatesAsync = streamable({
  url: 'http://xxx.xxx.xxx:xxx/updates'
});

Store for specific server event and allow credentials if needed:

Just provide event name as event and withCredentials properties in config object.

import { streamable } from 'svelte-streamable';

const postsAsync = streamable({
  url: 'http://xxx.xxx.xxx:xxx/updates',
  event: 'posts',
  withCredentials: true,
});

Pre-process recieved data with custom logic:

Just provide callback handler as second argument of streamable constructor and return the value:

import { streamable } from 'svelte-streamable';

const postsAsync = streamable({
  url: 'http://xxx.xxx.xxx:xxx/updates',
  event: 'posts'
}, ($posts) => {
  return $posts.reduce(...);
});

Asynchronous callback with cleanup logic:

This sematic formly looks like Svelte's derived store:

import { streamable } from 'svelte-streamable';

const postsAsync = streamable({
  url: 'http://xxx.xxx.xxx:xxx/updates',
  event: 'posts'
}, ($posts, set) => {

  // some async logic

    setTimeout(() => {
      set($posts);
    }, 1000);

    return (lastSubscriber) => {
        // cleanup logic
    console.log(lastSubscriber ?  'no more subscribers' : 'new update cleanup');
    };
});

Supporting several formats of the data:

Use format option with one of the folowing value: json (default), base64, urlencoded or raw.

import { streamable } from 'svelte-streamable';

const csvAsync = streamable({
  url: 'http://xxx.xxx.xxx:xxx/updates',
  format: 'urlencoded',
});

Get value in raw format instead of json (default) with custom preprocessing:

import { streamable } from 'svelte-streamable';

const csvAsync = streamable({
  url: 'http://xxx.xxx.xxx:xxx/updates',
  event: 'csv',
  format: 'raw',
}, ($csv) => {
  return CSVToArray($csv);
});

Using with svelte-asyncable

Streamable store contains a Promise to control async statuses (pending, fullfilled, rejected). To use the data in synchronous-way, you can use syncable store from svelte-asyncable package:

import { streamable } from 'svelte-streamable';
import { syncable } from 'svelte-asyncable';

const postsAsync = streamable(...); // contains Promise
const posts = syncable(postsAsync, []); // contains value

License

MIT © PaulMaly