title: Dynamically added script in body is executing before dynamically added script in head
body: <p>I have an HTML page, which making get request to the react page hosted in other domain. Once, i get page response, i copy JS from head section of requested page to head section of my page and same for script available in body section.</p>
  
  <p>Requested page is an react page which contain react and react-dom in head section and other JS chunk in body section, which will get copy to same section on my page.</p>
  
  <p>I thought, any script copied to head section of page immediately block page execution and once all script in head get executed then only scrip in body will execute.</p>
  
  <p>I'm getting intermittent client side error of "ReactDOM is not defined". It seems script copied to body is getting executed before script in head is fully executed.</p>
  
  <p>ReactJS and ReactDOM JS is in head section of page and chunk which throwing error is in body.</p>
  
  <pre><code>external "ReactDOM":1 Uncaught ReferenceError: ReactDOM is not defined
      at Object.faye (external "ReactDOM":1)
      at f (bootstrap:83)
      at Module.7n5H (tes1.ts:18)
      at f (bootstrap:83)
      at Object.0 (test2.ts:114)
      at f (bootstrap:83)
      at t (bootstrap:45)
      at Array.r [as push] (bootstrap:32)
      at 0.9efbe0e7cdf36824.chunk.js?_=1555361723703:1 faye @ external "ReactDOM":1 f @ bootstrap:83 7n5H @ tes1.ts:18 f @ bootstrap:83 0 @ test2.ts:114 f @ bootstrap:83 t @ bootstrap:45 r @ bootstrap:32 (anonymous) @ 0.9efbe0e7cdf36824.chunk.js?_=1555361723703:1
  </code></pre>