# Boolean Question

**URL:** <https://forum.kirupa.com/t/boolean-question/329423>\
**Category:** flash\
**Created:** [August 27, 2012, 4:22am UTC](https://forum.kirupa.com/t/boolean-question/329423 "2012-08-27T04:22:21Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![wortic](https://avatars.discourse-cdn.com/v4/letter/w/91b2a8/32.png) [@wortic](https://forum.kirupa.com/u/wortic)\
**Post date:** [August 27, 2012, 4:22am UTC](https://forum.kirupa.com/t/boolean-question/329423/1 "2012-08-27T04:22:21Z")

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How to check if boolean is undefined?  
I know that for numbers you can use if(isNaN(number)){some stuff}}  
I need some kind of isNaN for booleans…