@crikey/stores-select
v0.2.3
Published
Elegant methods for deriving sub-stores from existing stores.
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@crikey/stores-select
Elegant methods for deriving sub-stores from existing stores.
Supports deriving Writable
stores.
See @crikey/stores-select for full documentation.
API
Store creation functions:
select
- Create a sub store from an existing store
Selector functions:
by_index(index, default?)
- Utility method used to access array elements by indexby_key(key, default?)
- Utility method used to access Map elements by keyby_last_index(default?)
- Utility method used to access the last element in an arrayby_property(name, default?)
- Utility method used to access object properties by nameby_property_get(name, default?)
- Utility method used to access object properties by name (read only)by_set_element(element)
- Utility method used to add/remove elements from a setby_size(element)
- Utility method getting the size of a Set or Mapby_sparse_index(index, default?)
- 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' }