浮动标签 - 输入字段上方的标签

Question

我正在处理一个现有表单，我想在其中引入浮动标签。

我在堆栈溢出方面看到的许多解决方案都很棒，但需要 label 标签直接位于 <input> 标签下方。 For example here.

在我正在处理的表单上，我的label 标签位于<input> 标签的上方。输入标签位于单独的 div 中。 （我不允许移动这些标签 - 请不要问，限制应用程序！）。

无论如何，我可以用这种结构实现浮动CSS标签吗？

.test-field {
clear: both;
margin-bottom: 20px;
position: relative;
}


.test-field__input {
font-size: 0.875em;
line-height: 1;
-moz-appearance: none;
-webkit-appearance: none;
background-color: #f5f5f5;
border: 2px solid #eee;
border-radius: 4px;
color: grey;
height: calc((40 / 14) * 1em);
line-height: 1;
outline: 0;
padding: 0 8px;
vertical-align: top;
width: 100%;
}

/* // FOCUS */
.test-field__input:focus, 
.test-field__input ~ input:checked:focus {
border-color: #5d7199;
}

/* // DISABLED */
.test-field--disabled .test-field__input {
background-color: #e8e8e3;
cursor: not-allowed;
}

.test-field--disabled .test-field__flag, .test-field--disabled .test-field__label {
color: #d0d0cb;
}

/* // ERROR */
.test-field--error .test-field__input, .test-field--error .test-field__selection .atc-field__input {
border-color: #ff4436;
color: #ff4436;
}

/* // FLOATING LABEL */

.test-field--floating .test-field-input {
  position: relative;
  margin-bottom: 1.5rem;
}
.test-field__label {
  position: absolute;
  top: 0;
  padding: 7px 0 0 13px;
  transition: all 200ms;
  opacity: 0.5;
}

.test-field__input:focus + .test-field__label,
.test-field--floating .test-field__input:valid + .test-field__label {
  font-size: 75%;
  transform: translate3d(0, -100%, 0);
  opacity: 1;
}

<div class="test-field test-field--floating">
<label for="a" class="test-field__label">Input label</label>
  <input class="test-field__input" id="b"  type="text" value="" required>
</div>

Answer 1

这似乎是复制浮动标签的好方法，具有类似的 DOM 结构：

const floatField = document.querySelectorAll('.ej-form-field-input-textbox');

const floatContainer = document.querySelectorAll('.ej-form-field');


for (let i = 0; i < floatField.length; i++) {
    floatField[i].addEventListener('focus', () => {
     
    floatContainer[i].classList.add('active');
  });
};


for (let i = 0; i < floatField.length; i++) {
    floatField[i].addEventListener('blur', () => {
    floatContainer[i].classList.remove('active');
  });
};

.ej-form-field {
  border: solid 1px #ccc;
  padding: 0 8px;
  position: relative;
}
.ej-form-field input {
  border: 1px solid red;
  font-size: 16px;
  outline: 0;
  height: 30px;
/*   padding: 16px 0 10px; */
}

label {
  font-size: 16px;
  position: absolute;
  transform-origin: top left;
  transform: translate(0, 16px) scale(1);
  transition: all .1s ease-in-out;
  height: 40px;
}

.ej-form-field.active label {
  transform: translate(0, -6px) scale(.95);
  color: red;
  margin-left: 10px;
  background-color: #fff;
  border: 1px solid green;
  height: 20px;
}

<div id="floatContainer" class="ej-form-field">
  <label for="floatField">First name</label>
  <div>
    <input id="floatField" class="ej-form-field-input-textbox" type="text">
  </div>
</div>


<div id="floatContainer" class="ej-form-field">
  <label for="floatField">Last name</label>
  <div>
    <input id="floatField" class="ej-form-field-input-textbox" type="text">
  </div>
</div>