webstorage-decorators/README.md
2021-01-28 13:15:46 -05:00

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# WebStorage Decorators
A Javascript library that adds property decorators to sync a class property with the local or session storage.
## Quick Setup
1. Install with: `npm install --save webstorage-decorators`
2. Add the decorator to your property and use as normal!
```typescript
import {LocalStorage, SessionStorage} from 'webstorage-decorators';
export class MyCustomClass {
@LocalStorage({key: 'site_theme', default: 'light_theme'}) theme: string;
@SessionStorage({encryptWith: config.entryptionKey}) thisUser: User;
constructor() {
console.log(this.theme, localStorage.getItem('theme')); // Output: 'light_theme', 'light_theme'
console.log(this.user, localStorage.getItem('user')); // Output: null, undefined
user = {first: 'John', last: 'Smith', ...}
console.log(this.user, this.user == localStorage.getItem('user')); // Output: {first: 'John', last: 'Smith', ...}, true
}
}
```
## Caveats
Impure functions don't use the Object's setter preventing the storage from being updated. To prevent this use a pure
function or save it manually by reading the variable. (Reading triggers change detection & save if there are differences)
```typescript
@LocalStorage([1, 2]) example: number[];
example.push(3) // Impure & won't update storage
console.log(localStorage.getItem('example')) // Output: [1, 2];
example; // Trigger save
console.log(localStorage.getItem('example')) // Output: [1, 2, 3];
// OR
example = example.concat([3]); // Pure function requires you to use the setter triggering automatic saving
```