storage-facade
v4.0.6
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An simple way to store data in IndexedDB / localStorage / sessionStorage
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🔥 Storage facade
A TypeScript library providing a lightweight storage facade.
A storage facade provides a single storage API that abstracts over the actual storage implementation.
Library users can write an implementation of the synchronous
and/or asynchronous storage interface (localStorage / IndexedDB / ...)
extending the StorageInterface
abstract class.
This library does not contain a specific implementation for any storage, as it is a facade.
To create a specific implementation of the interface to any storage, you should implement the methods of the abstract class:
Async methods
initAsync<T extends StorageInterface>(setup: Setup<T>)
getItemAsync(key: string)
setItemAsync(key: string, value: unknown)
removeItemAsync(key: string)
clearAsync()
sizeAsync()
keyAsync(index: number)
- returns the name of the key by its indexdeleteStorageAsync()
And/or Sync methods
initSync<T extends StorageInterface>(setup: Setup<T>)
getItemSync(key: string)
setItemSync(key: string, value: unknown)
removeItemSync(key: string)
clearSync()
sizeSync()
keySync(index: number)
- returns the name of the key by its indexdeleteStorageSync()
Example: MockInterface
Implementing these methods will allow you to save and load values from storage in a convenient way, shown below.
In addition, iteration over entries is available.
Libraries using the Storage facade
IndexedDB
- storage-facade-indexeddb - An simple way to store data in IndexedDB.
localStorage
storage-facade-localstorage - If you need virtual storages inside
localStorage
that can be cleared without affecting other data stored inlocalStorage
. Supports caching.storage-facade-localstoragethin - Just delegation to
localStorage
. Supports caching.
sessionStorage
storage-facade-sessionstorage - If you need virtual storages inside
sessionStorage
that can be cleared without affecting other data stored insessionStorage
. Supports caching.storage-facade-sessionstoragethin - Just delegation to
sessionStorage
. Supports caching.
MockInterface
- storage-facade-mockinterface - MockInterface for Storage facade. Allows you to set a random delay in the interval for asynchronous operations. Used for testing.
MapInterface
- storage-facade-map - Just a wrapper for Map (MDN).
Installation
npm install storage-facade@4 storage-facade-mockinterface@4
Usage
Storage methods
.clear()
- removes all key-value pairs from the storage.getEntries()
async only, returns an array of promises to iterate.entries()
sync only, returns an array of key-value pairs.deleteStorage()
- delete storage.size()
- returns the number of key-value pairs.key(index: number)
- returns the name of the key by its index
The key
and size
methods can be used to create custom iterators.
'...Default' methods
The default values are used if the value in the storage is undefined
.
Default values are not stored in the storage, but in the instance.
Therefore, all these methods are synchronous (no need to use the await
keyword):
.addDefault(obj)
- adds keys and values from the passed object to the list of default values.setDefault(obj)
- replaces the list of default values with the given object.getDefault()
- returns an object containing default values.clearDefault()
- replaces a list of default values with an empty object
Examples
Async read/write/delete
import { createStorage } from 'storage-facade';
import { MockInterface } from 'storage-facade-mockinterface';
(async () => {
const storage = createStorage({
use: new MockInterface(), // Here is your interface
name: 'settings', // Storage name, optional
});
// If an error occurs at the initialization stage,
// it will be thrown at the first attempt
// to access the storage (read, write, all methods except
// 'addDefault, setDefault, getDefault, clearDefault')
// Write
storage.value = { data: [40, 42] };
// After the assignment, wait for the write operation to complete
await storage.value; // Successfully written
// Read value
console.log(await storage.value); // { data: [40, 42] }
// When writing, accesses to first-level keys are intercepted only,
// so if you need to make changes inside the object,
// you need to make changes and then assign it to the first level key.
// Get object
const updatedValue = (await storage.value) as Record<string, unknown>;
// Make changes
updatedValue.data = [10, 45];
// Update storage
storage.value = updatedValue;
await storage.value; // Successfully written
// Read value
console.log(
((await storage.value) as Record<string, unknown>).data
); // [10, 45]
// OR
const value = (await storage.value) as Record<string, unknown>;
console.log(value.data); // [10, 45]
// Delete value
delete storage.value;
await storage.value; // Successfully deleted
console.log(await storage.value); // undefined
storage.value = 30;
await storage.value;
console.log(await storage.value); // 30
// Clear storage
await storage.clear();
console.log(await storage.value); // undefined
// Delete storage
await storage.deleteStorage();
})();
Sync read/write/delete
import { createStorage } from 'storage-facade';
import { MockInterface } from 'storage-facade-mockinterface';
const storage = createStorage({
use: new MockInterface(), // Here is your interface
name: 'settings', // Storage name, optional
asyncMode: false,
// ^^^^^
});
// If an error occurs at the initialization stage,
// it will be thrown at the first attempt
// to access the storage (read, write, all methods except
// 'addDefault, setDefault, getDefault, clearDefault')
try {
storage.value = { data: [40, 42] };
console.log(storage.value); // { data: [40, 42] }
// When writing, accesses to first-level keys are intercepted only,
// so if you need to make changes inside the object,
// you need to make changes and then assign it to the first level key.
// Get object
const updatedValue = storage.value as Record<string, unknown>;
// Make changes
updatedValue.data = [10, 45];
// Update storage,
storage.value = updatedValue; // Ok
console.log((storage.value as Record<string, unknown>).data); // [10, 45]
delete storage.value;
console.log(storage.value); // undefined
storage.value = 30;
console.log(storage.value); // 30
storage.clear();
console.log(storage.value); // undefined
// Delete storage
storage.deleteStorage();
} catch (e) {
console.error((e as Error).message);
}
Async iteration .getEntries()
import { createStorage } from 'storage-facade';
import { MockInterface } from 'storage-facade-mockinterface';
(async () => {
const storage = createStorage({
use: new MockInterface(),
});
storage.value = 4;
await storage.value;
storage.other = 5;
await storage.other;
const promisesArray = await storage.getEntries();
const array = promisesArray.map(async (kv) => {
const [key, value] = await kv;
// ... add code here ...
return [key, value];
});
console.log(await Promise.all(array));
/*
[
['value', 4],
['other', 5],
]
*/
})();
Sync iteration .entries()
import { createStorage } from 'storage-facade';
import { MockInterface } from 'storage-facade-mockinterface';
const storage = createStorage({
use: new MockInterface(),
asyncMode: false,
});
try {
storage.value = 4;
storage.other = 5;
const array = storage
.entries()
.map(([key, value]) => {
// ... add code here ...
return [key, value];
});
console.log(array);
/*
[
['value', 4],
['other', 5],
]
*/
} catch (e) {
console.error((e as Error).message);
}
Async '...Default' methods
import { createStorage } from 'storage-facade';
import { MockInterface } from 'storage-facade-mockinterface';
(async () => {
const storage = createStorage({
use: new MockInterface(),
});
console.log(await storage.value) // undefined
storage.addDefault({ value: 9, other: 3 });
storage.addDefault({ value: 1, value2: 2 });
// Since `storage.value = undefined` the default value is used
console.log(await storage.value); // 1
console.log(await storage.value2); // 2
console.log(await storage.other); // 3
storage.value = 42;
await storage.value;
// When we set a value other than `undefined`,
// the default value is no longer used
console.log(await storage.value); // 42
storage.value = undefined;
await storage.value;
console.log(await storage.value); // 1
storage.value = null;
await storage.value;
console.log(await storage.value); // null
delete storage.value;
await storage.value;
console.log(await storage.value); // 1
// getDefault
console.log(storage.getDefault()); // { value: 1, value2: 2, other: 3 }
// Replace 'default'
storage.setDefault({ value: 30 });
console.log(await storage.value); // 30
console.log(await storage.value2); // undefined
// clearDefault
storage.clearDefault();
console.log(await storage.value); // undefined
console.log(await storage.value2); // undefined
})();
Sync '...Default' methods
import { createStorage } from 'storage-facade';
import { MockInterface } from 'storage-facade-mockinterface';
const storage = createStorage({
use: new MockInterface(),
asyncMode: false,
});
try {
console.log(storage.value) // undefined
storage.addDefault({ value: 9, other: 3 });
storage.addDefault({ value: 1, value2: 2 });
// Since `storage.value = undefined` the default value is used
console.log(storage.value); // 1
console.log(storage.value2); // 2
console.log(storage.other); // 3
storage.value = 42;
// When we set a value other than `undefined`,
// the default value is no longer used
console.log(storage.value); // 42
storage.value = undefined;
console.log(storage.value); // 1
storage.value = null;
console.log(storage.value); // null
delete storage.value;
console.log(storage.value); // 1
// getDefault
console.log(storage.getDefault()); // { value: 1, value2: 2, other: 3 }
// Replace 'default'
storage.setDefault({ value: 30 });
console.log(storage.value); // 30
console.log(storage.value2); // undefined
// clearDefault
storage.clearDefault();
console.log(storage.value); // undefined
console.log(storage.value2); // undefined
} catch (e) {
console.error((e as Error).message);
}
Limitations
Use only first level keys when writing
When writing, accesses to first-level keys (like storage.a =
,
but not storage.a[0] =
or storage.a.b =
) are intercepted only,
so if you need to make changes inside the object, you need to make changes
and then assign it to the first level key.
Assigning keys of the second or more levels will not give any effect.
sync:
// Read
console.log((storage.value as Record<string, unknown>).data); // Ok
// Write
// Don't do that
storage.value.data = 42; // no effect
Instead, use the following approach:
// Read
console.log((storage.value as Record<string, unknown>).data); // Ok
// Write
// Get object
const updatedValue = storage.value as Record<string, unknown>;
// Make changes
updatedValue.data = 42;
// Update storage
storage.value = updatedValue; // Ок
async:
// Read
console.log(
((await storage.value) as Record<string, unknown>).data
); // Ok
// Write
// Get object
const updatedValue = (await storage.value) as Record<string, unknown>;
// Make changes
updatedValue.data = 42;
// Update storage
storage.value = updatedValue;
await storage.value // Ок
Don't use banned key names
There is a list of key names that cannot be used because they are the same
as built-in method names: [clear
, deleteStorage
, size
, key
,
getEntries
, entries
, addDefault
, setDefault
, getDefault
, clearDefault
].
Use the keyIsNotBanned
function to check the key if needed.
import { createStorage, keyIsNotBanned } from 'storage-facade';
import { MockInterface } from 'storage-facade-mockinterface';
const storage = createStorage({
use: new MockInterface(),
asyncMode: false,
});
try {
const myNewKey = 'newKey';
if (keyIsNotBanned(myNewKey)) {
storage[myNewKey] = 42;
}
} catch (e) {
console.error((e as Error).message);
}
Keys are string
Only values of type string
can be used as keys.
Values for ...Default
methods
Values for [addDefault
, setDefault
] methods
should be of any structured-cloneable type (MDN).