Can someone explain this JavaScript mystery? -

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i writing simple recursive function in javascript , encountered weird behavior. @ first thought it's bug in browser, tried in firefox, chrome , ie9 , behave same way.

the html file below runs simple js function on page load. function recursive (calling once). function creates new array object , returns it. weird thing after function calls recursively, x , y reference same object, far understand should not happen. if uncomment last line before return x, alert "x == y" alert not shown.

<html xmlns="http://www.w3.org/1999/xhtml" > <head> <title>javascript weirdness...</title> <script type="text/javascript" language="javascript">     function recursivef(n) {         x = [ n ];          if (n > 0) {             y = recursivef(n - 1);             if (x == y)                 alert('x == y');         }          //if (n == 0) return [ n ];          return x;     } </script> </head><body onload="javascript:recursivef(1);"></body></html>

any hints why "x == y" alert appears in page?

x , y default global variables shared recursive calls of function. if want them local, declare them var keyword.


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