js capture all errors

JavaScript
<html>
   <head>
      <script>
         <!--
            window.onerror = function (msg, url, line) {
               alert("Message : " + msg );
               alert("url : " + url );
               alert("Line number : " + line );
            }
         //-->
      </script>
   </head>
   <body>
      <p>Click the following to see the result:</p>

      <form>
         <input type = "button" value = "Click Me" onclick = "myFunc();" />
      </form>
   </body>
</html>
Source

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