问动态创建新元素

EN

function f_color() {
  var x = document.getElementById('Tcolor1').value;
  window.alert(x);
  if (x == 0) {
    document.getElementById('input1').style.color = "black";
    document.getElementById('input2').style.color = "black";
    document.getElementById('input3').style.color = "black";
  }
  if (document.getElementById('Tcolor').value == 1) {
    document.getElementById('input1').style.color = "red";
    document.getElementById('input2').style.color = "red";
    document.getElementById('input3').style.color = "red";
  }
  if (document.getElementById('Tcolor').value == 2) {
    document.getElementById('input1').style.color = "blue";
    document.getElementById('input2').style.color = "blue";
    document.getElementById('input3').style.color = "blue";
  }
}

<button id="btn2">Add Another Class</button>

 
  <form>

    <select class="form-control" id="Tcolor" name="Tcolor" style="color:black;   
               
           font-size: 20px; " onchange="f_color()">

      <option value=0>black </option>

      <option value=1>red</option>

      <option value=2>blue </option>

    </select>

  </form>

  <form>
    <input id="input1" name="className"><br>
    <input id="input2" name="classTime"><br>
    <input id="input3" name="classNote"><br>
  </form>