<script>
function AutoScreen(el){
 
 var doc  = document.fullscreenElement;
 var moz  = document.mozFullScreenElement;
 var webkit = document.webkitFullscreenElement;
 var ms  = document.msFullscreenElement;
 
 if (!doc && !moz && !webkit && !ms) {
  fullscreen(el);
 } else {
  exitscreen();
 }
 
}

function fullscreen(el){
 
 if (el.requestFullscreen) {
  el.requestFullscreen();
 } else if (el.msRequestFullscreen) {
  el.msRequestFullscreen();
 } else if (el.mozRequestFullScreen) {
  el.mozRequestFullScreen();
    } else if (el.webkitRequestFullscreen) {
  el.webkitRequestFullscreen(Element.ALLOW_KEYBOARD_INPUT);
    }
 
}
function exitscreen(){
 
 var doc = document;
 
 if (doc.exitFullscreen) {
  doc.exitFullscreen();
    } else if (doc.msExitFullscreen) {
  doc.msExitFullscreen();
    } else if (doc.mozCancelFullScreen) {
  doc.mozCancelFullScreen();
    } else if (doc.webkitExitFullscreen) {
  doc.webkitExitFullscreen();
    }
}
</script>

<a href="#"onclick="AutoScreen(document.body)">FullScreen</a>​

풀스크린 검색시 나와있는 스크립트 정리 해봤습니다.