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What happens when you do not declare a variable in JavaScript?

Yes, this can be done. When you have a global scope, you can use a variable without declaring it. The following “no var” variable “points” will look at the scope chain, wince var keyword isn’t use −

<html>
   <body>
      <script>
         var rank = 5;
         points = 50;
         marks = 300;
         // Anonymous function
         (function() {
            points = 100; //overwrites global scope points
            var rank = 4; //new rank variable is created in this' function's scope
            var marks = 900;
            document.write(rank+"\r
"); //prints 4
            document.write(points+"\r
"); //prints 100
            document.write(marks+"\r
"); //prints 900
         })();
         document.write('<br/>');
         document.write('<br/>');
         document.write(rank+"\r
"); //prints 5
         document.write(points+"\r
"); //prints 100
         document.write(marks+"\r
"); //prints 300
      </script>
   </body>
</html>


Updated on 13-Jun-2020 09:23:31

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