title: Do we need to put "use strict" in external js files if our html file already has "use strict"?
body: <p>Do we need to put "use strict" in external js files if our html file (which imports the external js files) already has "use strict" ?</p>
  
  <p>And if our external js files do not have "use strict", are they still "strict" within a HTML file that has "use strict" ?</p>
  
  <p>Example:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
      &lt;title&gt;&lt;/title&gt;
      &lt;script&gt;
          "use strict";
          function f() {
              // calling File1 functions (File1 does not have "use strict"; at the top)
              // are the File1 functions "strict"?
          }
      &lt;/script&gt;
      &lt;script src="File1.js"&gt;&lt;/script&gt;
      &lt;script&gt;
          //by the way.. is it strict here ?
      &lt;/script&gt;
  &lt;/head&gt;
  &lt;body&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>