How to store objects in HTML5 localStorage

Last updated on Sep 10, 2022 by Suraj Sharma

In this tutorial, you will learn to store JavaScript objects and arrays in the Storage object in HTML5 window.localStorage.

window.localStorage property stores the data in the Web API Storage object.

localStorage allows you to access the Storage object from the global window object, for example

// Storage{length: 0}

// store a new key-value pair in localStorage

localStorage.setItem("animal", "cat")

localStorage.getItem("animal) // "cat"

The keys and the values stored in localStorage are always UTF-16 strings.

That's why, when we store an object value in localStorage, It gets converted into [object Object] string.

// store objects in localStorage

localStorage.setItem("emptyObject", {});

// getting the object from the localStorage,
//returns a string instead of the empty object

localStorage.getItem("emptyObject); // "[object Object]"

How to store objects in localStorage

To store objects or arrays, you have to

  1. use JSON.stringify() method to convert the objects or the arrays to JSON strings and then,

  2. store the strings to the Storage object using localStorage.setItem() method

const obj = {
  id: 1,
  name: "Suraj",
  city: "Bangalore"

const jsonString = JSON.stringify(obj);

localStorage.setItem("user", jsonString);

// "{\"id\":1,\"name\":\"Suraj\",\"city\":\"Bangalore\"}"

To get back the original object from the localStorage.getItem(), use the JSON.parse() method to parse the JSON string to the original JavaScript object.

const originalObj = JSON.parse(localStorage.getItem("user"));

// {id: 1, name: "Suraj", city: "Bangalore"}

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Suraj Sharma is a Full Stack Software Engineer. He holds a B.Tech degree in Computer Science & Engineering from NIT Rourkela.