Handle Local Storage

elf-local-storage.js

/**
 * Created by Charlie on 5/8/17.
 *
 * Use it like this:
 *   import { getByIndex } from '../assets/elf-local-storage';
 */

const ELF_TAG = 'elf';

const padNumber = function(numberToPad, width, padValue) {
    padValue = padValue || '0';
    numberToPad += '';
    if (numberToPad.length >= width) {
        return numberToPad;
    } else {
        return new Array(width - numberToPad.length + 1).join(padValue) + numberToPad;
    }
};

function saveByIndex(item, index) {
    if (typeof item === 'object') {
        item = JSON.stringify(item, null, 4);
    }
    const key = ELF_TAG + padNumber(index, 4, 0);
    localStorage.setItem(key, item);
}

function getByIndex(index) {
    const key = ELF_TAG + padNumber(index, 4, 0);
    return JSON.parse(localStorage.getItem(key));
}

function removeElfKeys() {
    for (var key in localStorage) {
        if (key.startsWith(ELF_TAG)) {
            localStorage.removeItem(key);
        }
    }
}

function clearLocalStorage() {
    localStorage.clear();
}

function getCount () {
    return localStorage.getItem('elven-count');
}

export {
  saveByIndex, 
  getByIndex, 
  removeElfKeys, 
  clearLocalStorage, 
  getCount
};