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Module @crikey/stores-select

@crikey/stores-select

Elegant methods for deriving sub-stores from existing stores.

Supports deriving Writable stores.

codecov

API

Store creation functions:
  • select - Create a sub store from an existing store

Selector functions:
  • by_index - Utility method used to access array elements by index
  • by_key - Utility method used to access Map elements by key
  • by_last_index - Utility method used to access the last element in an array
  • by_property - Utility method used to access object properties by name
  • by_property_get - Utility method used to access object properties by name (read only)
  • by_set_element - Utility method used to add/remove elements from a set
  • by_size - Utility method getting the size of a Set or Map
  • by_sparse_index - Utility method used to access sparse array elements by index

Installation

 
# pnpm
$ pnpm add @crikey/stores-select

# npm
$ npm add @crikey/stores-select

# yarn
$ yarn add @crikey/stores-select

Example

 
import {by_key, by_property, by_size, select} from "@crikey/stores-select";

const state = writable({
    user: {
        id: 5,
        username: 'Joe Blogs'
    },
    accounts: new Map([
        [2, { id: 2, name: 'First National' }],
        [3, { id: 3, name: 'Bank of mum and dad'}]
    ])
});

// Create nested derived stores to access user information
const user = select(state, by_property('user'));
const user_id = select(user, by_property('id'));
const user_username = select(user, by_property('username'));
console.log(get(user_id)); // 5
console.log(get(user_username)); // Joe Blogs

// These are stores, so everything is reactive
user_username.set('Joe Middlename Blogs');
console.log(get(user)); // { id: 5, username: 'Joe Middlename Blogs' }

// Create derived account stores
const accounts = select(state, by_property('accounts'));
const n_accounts = select(accounts, by_size());
console.log(get(n_accounts)); // 2

// Selectors can be chained to access deeply nested values
const first_national = select(state, by_property('accounts'), by_key(2));
console.log(get(first_national)); // { id: 2, name: 'First National' }

Index

Interfaces

Type aliases

Functions

Type aliases

Delete

Delete: (this: void) => void

Type declaration

    • (this: void): void

    • Parameters

      • this: void

      Returns void

Functions

by_chain

by_index

by_key

by_last_index

by_length

by_property

by_property_get

  • by_property_get<I, K>(key: K, def?: () => I[K]): ReadSelector<I, I[K]>

by_set_element

by_size

by_sparse_index

select

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