local-memory-storage
v1.0.5
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local-memory-storage
An in-memory typescript implementation of the Web Storage API that should be API-compatible with localStorage
.
In addition to supporting Web Storage methods (getItem
, setItem
, removeItem
, clear
), this library also closely matches localStorage's behaviour for enumerating and serializing its keys and values.
Usage Example
import { memoryStorage } from 'local-memory-storage';
memoryStorage.setItem('abc', 'xyz');
memoryStorage.getItem('abc'); //> 'xyz'
memoryStorage['abc']; //> 'xyz'
Object.keys(memoryStorage); //> ['abc']
JSON.stringify(memoryStorage); //> {"abc":"xyz"}
If separate instances are desired, the base class can imported instead
import { LocalMemoryStorage } from 'local-memory-storage';
const memoryStorage = new LocalMemoryStorage();
Sample usage for conditionally replacing localStorage
import { memoryStorage } from 'localmemorystorage';
const canUseLocalStorage = () => {
try {
const testKey = '__test_if_localstorage_is_available__';
localStorage.setItem(testKey, testKey);
localStorage.removeItem(testKey);
return true;
} catch (e) {
return false;
}
};
export const localStorageWithMemoryFallback = canUseLocalStorage()
? localStorage
: memoryStorage;
Motivation
Trying to access localStorage in incognito mode if your app is being embedded can result in this error:
Uncaught SecurityError: Failed to read the 'localStorage' property from 'Window': Access is denied for this document
One way to solve that would be to create a file like the above example to export a localStorageWithMemoryFallback
, and set eslint rules to disallow direct usage of localStorage
// eslintrc.js
module.exports = {
// ...
rules: {
// ...
"no-restricted-globals": [
{
name: "localStorage",
message: "Use `localStorageWithMemoryFallback` instead",
},
],
"no-restricted-properties": [
"error",
{
object: "window",
property: "localStorage",
message: "Use `localStorageWithMemoryFallback` instead",
},
],
},
};