JSFiddle - React, Tailwind, and code Playground

by cokar

HTML

<div class="form_wrap">
  <form action="">
    <fieldset>
      <legend>Log in</legend>
      <div class="form_cont">
        <label for="input01">User name</label>
        <input id="input01" class="user_name" type="text">
      </div>
      <div class="form_cont">
        <label for="input02">User password</label>
        <input id="input02" class="user_pw" type="password">
      </div>
    </fieldset>
  </form>
</div>

SCSS

.form_wrap {
	width: 500px;
  margin-left: 20px;
}
fieldset {
  border: 0;
  padding: 0;

	legend {
		padding: 20px 0 10px;
    font-weight: bold;
	}
	.form_cont {
		position: relative;
		border: 1px solid #dedede;
		border-radius: 15px;

		& ~ .form_cont {
			margin-top: 10px;
		}
		label {
			position: absolute;
			top: 17px;
			left: 20px;
			transition: all .5s;
			font-size: 16px;
      color: gray;
		}
		input {
			width: 100%;
			padding: 25px 20px 15px;
			border: 0;
			background-color: transparent;

			&:focus {
				outline: 0;
			}
		}

		&.on {
		  border: 1px solid #6fc2e1; 
		 
		  label {
			top: 4px;
			font-size: 12px;
		}
		}
	}
}

JavaScript

var $user_name = document.querySelectorAll('input')

function onFocus(e) {
  e.target.parentElement.classList.add("on");
  console.log(e.target.value);
}

function onBlur(e) {
  if (e.target.value == "") {
    e.target.parentElement.classList.remove("on");
  }
}

for (i = 0; i < $user_name.length; i++) {
  $user_name[i].addEventListener('focus', onFocus);
  $user_name[i].addEventListener('blur', onBlur);
}