Svelte Redux

Connect svelte components to a redux store.

Install

npm i svelte-redux

Usage

Connect the store

Assuming you already have a store set up, you need to connect it to your svelte component. You do this like so:

export default {
    store: connect(store, mapStateToData, mapDispatchToStore),

    // ...
};

If you've used redux with react, this should be quite familiar.

Map the state

The mapStateToData property is a function that, given the current state, returns the data you want to consume in this component.

In this very simplistic example, our whole state is just a number (we're building a simple counter) so you might map it as below:

const mapStateToData = state => {
    return {
        count: state,
    };
};

Using the data

Now that we've mapped our state to count, we can access it in the template like you would with local state, however it is prepended with a $.

<h1>
    Clicked {{$count}} times
</h1>

Dispatching actions

In order to dispatch actions, you must first map a dispatch function to the store.

const mapDispatchToStore = dispatch => {
    return {
        increment: () => dispatch({ type: 'INCREMENT' }),
        decrement: () => dispatch({ type: 'DECREMENT' }),
    };
};

And now we can access these functions in the template via the store

<button on:click="store.increment()">+</button>
<button on:click="store.decrement()">-</button>

Optimisations

At this point everything should be working, there are however a few things we can change for convenience.

The mapDispatchToStore function is quite verbose given the simple goal so we can instead use the shorthand:

const mapDispatchToStore = {
    increment: () => ({ type: 'INCREMENT' }),
    decrement: () => ({ type: 'DECREMENT' }),
};

Passing store to connect every time is slightly inconvenient and requires all your components to know about store. We can use the bindConnect to make this slightly nicer.

const connect = bindConnect(store);

// ...

export default {
    store: connect(mapStateToData, mapDispatchToStore),
};

And now we can use this connect function instead of the one imported from svelte-redux

Full Example

store.js

import { createStore } from 'redux';
import { bindConnect } from 'svelte-redux';

const store = createStore((state = 0, action) => {
    switch (action.type) {
        case 'INCREMENT':
            return state + 1;
        case 'DECREMENT':
            return state - 1;
        default:
            return state;
    }
});

export const connect = bindConnect(store);

Counter.html

<h1>
    Clicked {{$count}} times
</h1>
<button on:click="store.increment()">+</button>
<button on:click="store.decrement()">-</button>

<script>
    import { connect } from './store';

    const mapStateToData = state => {
        return {
            count: state,
        };
    };

    const mapDispatchToStore = {
        increment: () => ({ type: 'INCREMENT' }),
        decrement: () => ({ type: 'DECREMENT' }),
    }

    export default {
        store: connect(mapStateToData, mapDispatchToStore)
    }
</script>