Test if a variable exists

var foo = "bar";

if ( typeof( window[ 'foo' ] ) != "undefined" ) {
   document.write("foo is defined")
   } 
else {
   document.write("foo is undefined")
   }
Here is the result for "foo" :

And for fubar :

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Written and compiled by Réal Gagnon ©1998-2010
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