JavaScript에서 Radio Button 다루기

Radio Button 체크 여부 확인

js

function checkForm(){
  var f = document.formname;
  var checked = false;
  for(i=0; i <f.Blood.length; i++){ 
    if(f.Blood[i].checked) checked = true;
  }
  if(!checked){ 
    alert('혈액형을 넣어주세요'); 
    f.Blood[0].focus(); 
    return false;
  }
  return true;
}

html

 <form name="formname" onSubmit="return checkForm()">
   <input type="radio" name="Blood" value="A"> A형
   <input type="radio" name="Blood" value="AB"> AB형
   <input type="radio" name="Blood" value="B"> B형
   <input type="radio" name="Blood" value="O"> O형
   <button type="submit">보내기</button>
 </form>

See the Pen 자바스크립트 radio button 다루기 by younghyeong ryu (@wangta69) on CodePen.