webstorage-decorators/lib/webstorage.js

98 lines
3.4 KiB
JavaScript

import * as crypto from 'crypto-js';
/**
* Automatically syncs localStorage with the decorated property.
*
* **Example**
* ```
* class Example {
* @LocalStorage() lastLogin: string;
* @LocalStorage(false, {key: '_hideMenu'}) hideMenu: boolean;
* }
* ```
*
* @param defaultValue Default value to return if property does no exist inside localStorage.
* @param opts Any additional options
*/
export function LocalStorage(defaultValue, opts = {}) {
opts.default = defaultValue;
return decoratorBuilder(localStorage, opts);
}
/**
* Automatically syncs sessionStorage with the decorated property.
*
* **Example**
* ```
* class Example {
* @SessionStorage() lastLogin: string;
* @SessionStorage(false, {key: '_hideMenu'}) hideMenu: boolean;
* }
* ```
*
* @param defaultValue Default value to return if property does no exist inside sessionStorage.
* @param opts Any additional options
*/
export function SessionStorage(defaultValue, opts = {}) {
opts.default = defaultValue;
return decoratorBuilder(sessionStorage, opts);
}
/**
* **Internal use only**
*
* Fetch variable from storage & take care of any defaults, object definitions, encryption & serialization
*
* @param storage Web Storage API
* @param opts Any additional options
*/
function fromStorage(storage, opts) {
let storedVal = storage.getItem(opts.key);
if (storedVal == null || storedVal == "" || storedVal == "undefined") {
if (opts.default == null)
return null;
if (opts.default != 'object')
return opts.default;
if (opts.default.constructor != null)
return Object.assign(new opts.default.constructor(), opts.default);
let temp = Object.assign({}, opts.default);
Object.setPrototypeOf(temp, Object.getPrototypeOf(opts.default));
return temp;
}
storedVal = JSON.parse(storedVal);
if (opts.encryptWith != null)
storedVal = JSON.parse(crypto.AES.decrypt(storedVal, opts.encryptWith).toString(crypto.enc.Utf8));
if (typeof storedVal != 'object' || !Array.isArray(storedVal))
return storedVal;
if (opts.default != null && opts.default.constructor != null)
return Object.assign(new opts.default.constructor(), opts.default, storedVal);
return Object.assign({}, opts.default, storedVal);
}
/**
* **Internal use only**
*
* Overrides the properties getter/setter methods to read/write from the provided storage endpoint.
*
* @param storage Web Storage API
* @param opts Any additional options
*/
function decoratorBuilder(storage, opts) {
return function (target, key) {
if (!opts.key)
opts.key = key;
let field = fromStorage(storage, opts);
Object.defineProperty(target, key, {
get: function () {
if (field != fromStorage(storage, { key: opts.key, encryptWith: opts.encryptWith }))
target[key] = field;
return field;
},
set: function (value) {
field = value;
if (value == null)
storage.removeItem(opts.key);
if (opts.encryptWith != null)
value = crypto.AES.encrypt(JSON.stringify(value), opts.encryptWith).toString();
storage.setItem(opts.key, JSON.stringify(value));
}
});
};
}
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