taking javascript into an external file and calling a function from it

Question

I have made a working webpage but when i try to take the jscript into an external file it no longer is called. i have put in the code in my header to include the file name but still unable to call it. Here is my jscript please help me out by the way just a quick edit I got the isMobile function from here http://www.abeautifulsite.net/blog/2011/11/detecting-mobile-devices-with-javascript/

<script>        
    var isMobile = {
      Android: function() {
        return navigator.userAgent.match(/Android/i);
      },
      BlackBerry: function() {
        return navigator.userAgent.match(/BlackBerry/i);
      },
      iOS: function() {
        return navigator.userAgent.match(/iPhone|iPad|iPod/i);
      },
      Opera: function() {
        return navigator.userAgent.match(/Opera Mini/i);
      },
      Windows: function() {
        return navigator.userAgent.match(/IEMobile/i);
      },
      any: function() {
        return (isMobile.Android() || isMobile.BlackBerry() || isMobile.iOS() || isMobile.Opera() || isMobile.Windows());
      }
    };
    function load()
    {
      var w=((screen.availWidth)/50)*49;
      var h=(w/4)*3;
      if( isMobile.any() ){
        var t=w;
        w=h;
        h=t;

      }
      var a=document.getElementById('banner');
      a.style.width=w+'px';
      a.style.height=(h/4)+'px';
      var b=document.getElementById('main');
      b.style.width=w+'px';
      b.style.height=Math.round((h/7)*4)+'px';
    }
  </script>

Answer 1

When referencing an external JavaScript file, its contents should not be surrounded by a <script> tag. The <script> tag in the main file is what informs the browser that the contents should be parsed as JavaScript. Remove the surrounding <script> tag from the external file.

Proper reference in the main file:

<script type='text/javascript' src='path/to/external.js'></script>

The language='JavaScript' attribute has been deprecated and is unnecessary. You may include type='text/javascript' .

The contents of the external file should contain only JavaScript code, not surrounding <script> tags as in:

// File external.js
alert('Look, no script tag!');