Storage Extension

npm

This is the official storage extension for Harlem. The storage extension adds the ability to sync store state to/from localStorage or sessionStorage.

Getting Started

Follow the steps below to get started using the storage extension.

Installation

Before installing this extension make sure you have installed @harlem/core.

yarn add @harlem/extension-storage
npm install @harlem/extension-storage

Registration

To get started simply register this extension with the store you wish to extend.

import storageExtension from '@harlem/extension-storage';

import {
    createStore
} from '@harlem/core';

const STATE = {
    firstName: 'Jane',
    lastName: 'Smith'
};

const {
    state,
    getter,
    mutation,
    startStorageSync,
    stopStorageSync,
    clearStorage
} = createStore('example', STATE, {
    extensions: [
        storageExtension({
            type: 'local',
            prefix: 'harlem',
            sync: true,
            exclude: [],
            serialiser: state => JSON.stringify(state),
            parser: value => JSON.parse(value)
        })
    ]
});















 
 
 


 
 
 
 
 
 
 
 


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The storage extension adds several new methods to the store instance (highlighted above).

Usage

Options

The storage extension method accepts an options object with the following properties:

  • type: string - The type of storage interface to use. Acceptable values are local or session. Default value is local.
  • prefix: string - The prefix to use on the storage key. The storage value will be in the form ${prefix}:${storeName}. Default value is harlem.
  • sync: boolean - Whether to automatically sync changes from the storage interface back to the store. Default value is true.
  • exclude: string[] - A list of mutation names to exclude from triggering a storage sync event.
  • serialiser: unknown => string - A function to serialise the store to string. The default behaviour is JSON.stringify.
  • parser: string => unknown - A function to serialise the storage string to a state structure. The default behaviour is JSON.parse.

Manually starting/stopping sync

The startStorageSync and stopStorageSync methods can be used to start or stop sync behaviour.

Clearing storage

Use the clearStorage method to clear all stored data relating to this store.

Considerations

Please keep the following points in mind when using this extension:

  • The default behaviour for serialising/parsing only supports JSON-compatible types. For non-JSON-compatible types please specify a custom serialiser/parser. See hereopen in new window for a list of JSON-compatible types.