timer_gear exist only in case if I press some button (until 5 sec). But there is another function it can be called any time. In this function I clear the timer and restart it. But first I have to check if the object exists otherwise I get this error:
Uncaught ReferenceError: timer_gear is not defined

Could you help me to solve this? These does not work.

if(timer_gear!=undefined)clearTimeout(timer_gear);



if(timer_gear)clearTimeout(timer_gear);

EDIT1:
first I misspelled my question: if(!timer => if(timer
EDIT2:

the full code is:

function hide_gear(){

    $('#gear_div').animate({opacity: 0}, 1000);

    delete timer_gear; //EDIT3: destroy object

}

...

/*gear*/

$('#gear').click(function(){

    $('#gear_div').animate({

        opacity: 1,

      }, 1000, function() {

        timer_gear = setTimeout(hide_gear();,5000);

      });

});

$('#gear').mousemove(function(){

    if( ? ? ? )

    {

        clearTimeout(timer_gear);

        timer_gear = setTimeout(hide_gear();,5000);

    }



});

Results:

timer_gear// Uncaught ReferenceError timer_gear is not defined

timer_gear != undefined // Uncaught ReferenceError: timer_gear is not defined

typeof timer_gear !== undefined // WORKS

typeof timer_gear != undefined // WORKS, just tired it

var timer_gear; //at the begining - WORKS, but I did not wanted a new variable if its not necessary

thank you for answers!