Press the same keystroke twice

Thunder never strikes...

var twice_37 = 0;

$(document).on('keydown', function( e ){
  var key = e.which;  
  if(key==37){

    twice_37 += 1; // almost :)   

    if(twice_37==2){
      alert('Do something! you pressed twice left!');
    }   

    setTimeout(function(){    
      twice_37 = 0; // Reset 
    }, 1000);    

  }
});