Get cookie with react

Question

You can use js-cookie package and can install it using npm install js-cookie --save command.

import React from 'react';
import Cookies from 'js-cookie';

class App extends React.Component {
     this.state = {
        username: Cookies.get('username')
     }

//  more code....
}  

Documentation : https://github.com/js-cookie/js-cookie

NPM : https://www.npmjs.com/package/js-cookie

If all you want is to get the cookie value by key, I would suggest using plain javascript without any dependencies.

In this example, it gets the cookie value by the key "username" with the help of Regex.

let cookieValue = document.cookie.replace(/(?:(?:^|.*;\s*)username\s*\=\s*([^;]*).*$)|^.*$/, "$1");

https://developer.mozilla.org/en-US/docs/Web/API/document/cookie#Example_2_Get_a_sample_cookie_named_test2

I'd recommend using universal-cookie as its simpler to use. Mind you, cookies have nothing to do with React. They are stored on the browser and you could use the browser's default API to get cookies.

Here is an example how you can use universal-cookies

import React from 'react';
// other imports...
import Cookies from 'universal-cookie';

const cookies = new Cookies();

class App extends React.Component {
     this.state = {
        username: cookies.get('username')
     }

//  more code....   

Source: https://www.npmjs.com/package/universal-cookie

There is no need for a third party npm package. You can use plain JS to extract the cookie. Here is a custom function for that:

function getCookie(key) {
  var b = document.cookie.match("(^|;)\\s*" + key + "\\s*=\\s*([^;]+)");
  return b ? b.pop() : "";
}

You can also use the method below without any 3rd party package as documented in developer.mozilla.org :

document.cookie
  .split('; ')
  .find(row => row.startsWith('YOUR-COOKIE='))
  .split('=')[1];