FileReader class is HTML5 generation of function. < html> < head>FileReader check < script type="text/javascript"> < !-- (function (){ if(window.FileReader){ element.value = "OK"; }else{ element.value = "NG"; } })(); //--> < /script> < /head> < body> < input type="text" id="edit_box00_00" value=""> < /body> < /html>