React dom when searching the element not getting node

I have react code added with plain html when i am searching elements but not getting the hidden type input type element Please any on know why this happens ?

<input type="hidden" id="shop-domain" value="{{shop.domain}}" />

when i am searching in react code this html element not getting and throw an errror.

shop_domain = document.getElementById(‘shop-domain’).value();

following error throws

Uncaught TypeError: Cannot read properties of null (reading 'value')
    at <anonymous>:1:39
(anonymous) @ VM395:1

hello @SpadeX
This happens because there is a Lifecycle of React-Component

if you try to access elements in a JSX before render method is called by react, That element will be null

and since you are just accessing the .value
value is a property not a function

without checking whether it exits or not.
you will encounter an ERROR:
Cannot read properties of null

Solution

in functional component put your code inside useEffect hook

 useEffect(() => {
    console.log(document.querySelector("#shop-domain").value);
  }, []);

In class component you can write it on componentDidMount method

class App extends React.Component {

  constructor(props) {
    super(props);
    this.state = { shop: 'lightgreen' };
  }
 
 componentDidMount() {
   const shop_domain = document.getElementById(‘shop-domain’).value;
   console.log(shop_domain)
 }

  render() {
    return (<input type="hidden" id="shop-domain" value={this.state.shop} />)
  }

}