javascript - 如果选择的值是 SMTH，则跨度/隐藏输入

Question

我已经选择了选项并且有很多输入。如果我选择选项(例如“USER”)，我需要跨越准备好的输入，如果选择另一个选项，我需要再次隐藏它。

<form class="form-signup" action="admin_users.php" method="POST" id="payment-form">

                <div class="well well-sm">
               	<h3 class="form-signin-heading"> Create

                <select id="selectlist" name="selectproduct" >
                    <option value="1">User</option>
                    <option value="2">Admin</option>
                    <option value="3">Smth else</option>
                    <option value="4">Smth else of else</option>

                  </select>
                  </h3>

               	<div class="form-group">
                  <div class="col-xs-12">
               		<input  class="form-control" type="text" name="username" id="username" placeholder="İstifadəçi" value="first input" required autofocus>
</div>
<div> &nbsp </div>
                  <div class="col-xs-12">
               		<input type="text" class="form-control" id="fname" name="fname" placeholder="Ad" value="second input" required>
</div>
<div> &nbsp </div>

	            <input class='btn btn-primary' type='submit' name='addUser' value='Create user' />
              </div>
               </form>

Answer 1

$( "#selectlist" ).change(function(event) {
  if (this.value == 1 || this.value == 2) {
    $(".form-control").show();
  } else {
    $(".form-control").hide();
  }
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form class="form-signup" action="admin_users.php" method="POST" id="payment-form">

                    <div class="well well-sm">
                   	<h3 class="form-signin-heading"> Create

                    <select id="selectlist" name="selectproduct" >
                        <option value="1">User</option>
                        <option value="2">Admin</option>
                        <option value="3">Smth else</option>
                        <option value="4">Smth else of else</option>

                      </select>
                      </h3>

                   	<div class="form-group">
                      <div class="col-xs-12">
                   		<input class="form-control" type="text" name="username" id="username" placeholder="İstifadəçi" value="first input" required autofocus>
    </div>
    <div> &nbsp </div>
                      <div class="col-xs-12">
                   		<input type="text" class="form-control" id="fname" name="fname" placeholder="Ad" value="second input" required>
    </div>
    <div> &nbsp </div>

    	            <input class='btn btn-primary' type='submit' name='addUser' value='Create user' />
                  </div>
                   </form>