ionic-framework/ionic/platform/storage/local-storage.ts

import {StorageEngine} from './storage';


/**
 * @name LocalStorage
 * @description
 * The LocalStorage storage engine uses the browser's local storage system for
 * storing key/value pairs.
 *
 * Note: LocalStorage should ONLY be used for temporary data that you can afford to lose.
 * Given disk space constraints on a mobile device, local storage might be "cleaned up"
 * by the operating system (iOS).
 *
 * For guaranteed, long-term storage, use the SqlStorage engine which stores data in a file.
 *
 * @usage
 * ```ts
 * import {Page, Storage, LocalStorage} from 'ionic/ionic';
 * @Page({
 *   template: `<ion-content></ion-content>`
 * });
 * export class MyClass{
 *  constructor(){
 *    this.local = new Storage(LocalStorage);
 *    this.local.set('didTutorial', true);
 *  }
 *}
 *```
 * @demo /docs/v2/demos/local-storage/
 * @see {@link /docs/v2/platform/storage/ Storage Platform Docs}
 */
export class LocalStorage extends StorageEngine {
  constructor() {
    super();
  }

/**
 * Get the value of a key in LocalStorage
 * @param {String} key the key you want to lookup in LocalStorage
 */
  get(key) {
    return new Promise((resolve, reject) => {
      try {
        let value = window.localStorage.getItem(key);
        resolve(value);
      } catch(e) {
        reject(e);
      }
    });
  }

/**
 * Set a key value pair and save it to LocalStorage
 * @param {String} key the key you want to save to LocalStorage
 * @param {Any} value the value of the key you're saving
 */
  set(key, value) {
    return new Promise((resolve, reject) => {
      try {
        window.localStorage.setItem(key, value);
        resolve();
      } catch(e) {
        reject(e);
      }
    });
  }

/**
 * Remove a key from LocalStorage
 * @param {String} key the key you want to remove from LocalStorage
 */
  remove(key) {
    return new Promise((resolve, reject) => {
      try {
        window.localStorage.removeItem(key);
        resolve();
      } catch(e) {
        reject(e);
      }
    });
  }
}