Untitled

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width">
  <title>JS Bin</title>
</head>
<body onload="onclick=_onCreate()">
  <script>
    function _onCreate(){
      setTimeout(function(){

        //create button1
        var selectButton = document.createElement('button');
        selectButton.innerHTML = "셀렉트";
        selectButton.setAttribute('onclick','_createSelect()');

        //create button2
        var checkButton = document.createElement('button');
        checkButton.innerHTML = "체크";
        checkButton.setAttribute('onclick','_createCheckBox()');

        //create button3
        var textButton = document.createElement('button');
        textButton.innerHTML = "텍스트";
        textButton.setAttribute('onclick','_createInputText()');

        //create wrapper div
        var wrapper = document.createElement('div');
        document.body.appendChild(wrapper);
        wrapper.appendChild(selectButton);
        wrapper.appendChild(checkButton);
        wrapper.appendChild(textButton);

      },500);
    }

    var index = 1; //index in selectbox
    var selectBox, divCheck, divText;

    function _createSelect(){

      if(document.getElementById('divSelect') == null){
        var divSelect = document.createElement('div');
        divSelect.setAttribute('id','divSelect');
        document.body.appendChild(divSelect);

        selectBox = document.createElement('select');
        divSelect.appendChild(selectBox);
      }
      var option = document.createElement('option');
      option.innerHTML = "옵션"+ index++;
      selectBox.appendChild(option);

    }

    function _createCheckBox(){

      if(document.getElementById('divCheck') == null){
        console.log('null');

        divCheck = document.createElement('div');
        divCheck.setAttribute('id','divCheck');
        document.body.appendChild(divCheck);

      }
      var checkbox = document.createElement('input');
      checkbox.setAttribute('type','checkbox');
      divCheck.appendChild(checkbox);
    }

    function _createInputText(){

      if(document.getElementById('divText') == null){
        divText = document.createElement('div');
        divText.setAttribute('id','divText');
        document.body.appendChild(divText);
      }

      var inputText = document.createElement('input');
      inputText.setAttribute('type','text');
      divText.appendChild(inputText);
    }
  </script>
</body>
</html>