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JavaScript function addes value to itself as a variable !

I need to understand below function.

var guid = function() {

      var nav = window.navigator;
      var screen = window.screen;
      var guid = nav.mimeTypes.length;
      guid += nav.userAgent.replace(/\D+/g, '');
      guid += nav.plugins.length;
      guid += screen.height || '';
      guid += screen.width || '';
      guid += screen.pixelDepth || '';

      return guid;

What is the line guid += ? How can function add to itself as a variable ?

1 Answer

Chris Shaw
Chris Shaw
26,676 Points

Hi Ajinkya,

The value isn't been assigned to the function as that is impossible, the guid function has a locally scoped variable called guid which new values are been appended to.

Ajinkya, if you pull up your browser's console and check this out: http://jsfiddle.net/vztmLL4h/ ; You'll see that guid is undefined from within the function's local scope, exactly as Chris has explained.

oh my mistake. thanks for spotting :)