jquery melaksanakan papan kekunci kiri dan kanan halaman memusing effects_jquery

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$(document).ready(function(){ 
  var prevpage=$("#pre").attr("href"); 
  var nextpage=$("#next").attr("href"); 
  $("body").keydown(function(event){ 
   if(event.keyCode==37 && prevpage!=undefined) location=prevpage; 
   if(event.keyCode==39 && nextpage!=undefined) location=nextpage; 
    
  }); 
 });