JSFiddle - React, Tailwind, and code Playground

JavaScript

function setCookie(name, value, days) {
    var d = new Date;
    d.setTime(d.getTime() + 24*60*60*1000*days);
    document.cookie = name + "=" + value + ";path=/;expires=" + d.toGMTString();
}

function getCookie(name) {
    var v = document.cookie.match('(^|;) ?' + name + '=([^;]*)(;|$)');
    return v ? v[2] : null;
}

function getUser() {
  let user = getCookie('ds_user')
  if (!user) {
    return null
  }
  return JSON.parse(atob(user))
}


const mockUser = {
    user: {
        id: "1671",
        email: "[email protected]",
        username: "art",
        firstName: "Art",
        lastName: "Vandalay",
        phone: null,
        admin: true,
        title: "",
        guid: "u0000ZDCF4",
        vendorUser: false,
        lastLogin: "2019-06-07 18:52:11",
        defaultStoreId: "6",
    },
    store: {
        storeId: 6,
        name: "Demo Store",
        marketId: 13
    }
}

setCookie('ds_user', JSON.stringify(btoa(mockUser)), 7)

getUser()