Simple localStorage function with Cookie fallback for older browsers. ES6 syntax, so assuming transpiler for older browsers

SimpleStore.js

/**
 * Simple localStorage with Cookie Fallback
 * v.1.0.0
 *
 * USAGE:
 * ----------------------------------------
 * Set New / Modify:
 *   store('my_key', 'some_value');
 *
 * Retrieve:
 *   store('my_key');
 *
 * Delete / Remove:
 *   store('my_key', null);
 */
 
const store = (key, value) => {
 
    const lsSupport = !!localStorage;  
   
    if (typeof value !== "undefined" && value !== null) {
        if ( typeof value === 'object' ) {
            value = JSON.stringify(value);
        }
        return lsSupport ? localStorage.setItem(key, value) : createCookie(key, value, 30);
    }
    
    if (typeof value === "undefined") {
        const data = lsSupport ? localStorage.getItem(key) : readCookie(key); 
        try {
           const dataObj = JSON.parse(data);
           return dataObj;
        } catch(e) {
           return data;
        }
    }
    
    if (value === null) {
        return lsSupport ? localStorage.removeItem(key) : createCookie(key, '', -1);
    }
    
    /**
     * Creates new cookie or removes cookie with negative expiration
     * @param  key       The key or identifier for the store
     * @param  value     Contents of the store
     * @param  exp       Expiration - creation defaults to 30 days
     */
    
    const createCookie = (key, value, exp) => {
        const expires = "; expires=" + (new Date(Date.now() + (exp * 24 * 60 * 60 * 1000))).toUTCString();
        document.cookie = key + "=" + value + expires + "; path=/";
    }
    
    /**
     * Returns contents of cookie
     * @param  key       The key or identifier for the store
     */
    
    const readCookie = (key) => (document.cookie.match('(^|; )'+key+'=([^;]*)')||0)[2];
    
};