title: Curtain menu is not recognizing my javascript source code
body: <p>I am using w3school as my learning portal, but now I am facing problem. When I run code with all source code in html file, it works fine. But when I put the javascript source code into external js. file, it nothing happens.</p>
  
  <p>The functional one is here : <a href="https://jsfiddle.net/agentkocicka/es6d05rh/" rel="nofollow noreferrer">JSFiddle</a></p>
  
  <p>The javascript code is:</p>
  
  <pre><code>    function openNav() {
    document.getElementById("myNav").style.width = "100%";
  }
  
  function closeNav() {
    document.getElementById("myNav").style.width = "0%";
  }
  </code></pre>
  
  <p>This code I replace with <code>&lt;script src="/js/w3school_index.js"&gt;&lt;/script&gt;</code> because the file is located in directory named "js"</p>
  
  <p>Should I call the source code when I call the method in the HTML file? Or it is enought to call it like I have? Or should I add some code into javascript file?</p>