Javascript function without any code in it -

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i found following javascript code snippet part of popup window, causing browser ask if want close window.

window.onbeforeunload = function() {     settimeout(function() {         window.onbeforeunload = function() {};         settimeout(function() {             document.location.href = 'index.html';         }, 500);     },5);     return ''; };

i wondering these things:

  • why use function without code in ( code line 3 )
  • why use window.onbeforeunload inside second time?

or try obfuscate purpose ?


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