title: Where do I get the value for `shopOrigin` when using Shopify app bridge?
body: <p>Throughout the documentation for the new App Bridge, Shopify refers to the <code>shopOrigin</code> value and how it's used to configure the Provider from <code>app-bridge-react</code> but they never specify how to get this value?</p>
  
  <p><a href="https://i.stack.imgur.com/M5VX5.png" rel="noreferrer"><img src="https://i.stack.imgur.com/M5VX5.png" alt="enter image description here"></a></p>
  
  <p>The react app is loaded inside of an iframe and the src includes the <code>shopOrigin</code> value as a query string param called <code>shop</code>, but when I try the following code I get the error <code>window is not defined</code>:</p>
  
  <pre><code>const params = queryString.parse(window.location.search);
  const config = {
    apiKey: process.env.SHOPIFY_API_KEY,
    shopOrigin: params.shop,
  };
  </code></pre>
  
  <p>1) Why would I be getting <code>window is not defined</code> in javascript code running in a browser?! This makes no sense to me
  2) If this value can be read from of the provided libraries such as <code>@shopufy/app-bridge-react</code> please tell me how</p>