<div id="container"></div>
@import url('https://fonts.googleapis.com/css?family=Lato:300,400,700');
@import url('https://fonts.googleapis.com/css?family=Inconsolata');
$beige: #FFDBB5;
$pink: #EF767A;
body {
  background: $pink;
  font-family: 'Lato', sans-serif;
  overflow: hidden;
}

#container {
  height: 100vh;
}

.rules,
.app,
#container {
  display: flex;
  justify-content: center;
}

#container,
.app {
  align-items: center;
}

.app {
  flex-direction: column;
  height: 400px;
  
  ul {
    padding: 0;
  }
  
  li {
    color: $beige;
    letter-spacing: 1px;
    font-weight: 300;
    font-size: 16px;
    margin: 5px;
  }
  .passed {
    color: rgba(white, 0.3);
    transition: 0.4s all;
    text-decoration: line-through;
  }
  .missing {
    color: $beige;
    transition: 0.4s all;
  }
}

.rules {
  width: 330px;
}

input,
button {
  border: none;
  outline: none;
}

input {
  background: none;
  width: 260px;
  border-bottom: 3px solid $beige;
  color: white;
  font-size: 27px;
  transition: 0.4s all;
  text-align: center;
  &:focus {
    width: 330px;
    transition: 0.4s all;
  }
}

::placeholder {
  color: rgba(white, 0.4);
  ;
}

button {
  background: $beige;
  width: 120px;
  height: 30px;
  font-size: 15px;
  color: $pink;
  border-radius: 4px;
  transition: 0.4s all;
  cursor: pointer;
  &:disabled {
    opacity: 0.5;
    transition: 0.4s all;
    &:hover {
      animation: 500ms shake;
    }
  }
  &:hover {
    animation: 500ms nod infinite;
  }
}

@keyframes shake {
  0% {
    transform: rotate(2deg);
  }
  50% {
    transform: rotate(-3deg);
  }
  70% {
    transform: rotate(3deg);
  }
  100% {
    transform: rotate(0deg);
  }
}

@keyframes nod {
  0% {
    transform: translateY(0);
  }
  50% {
    transform: translateY(2px);
  }
  100% {
    transform: translateY(0px);
  }
}

footer {
  position: absolute;
  bottom: 0;
  right: 0;
  padding: 13px;
  font-family: 'Inconsolata', monospace;
  font-size: 14px;
  color: rgba(white, 0.6);
  a {
    color: $beige;
  }
}
View Compiled
class PasswordChecker extends React.Component {
  constructor(props) {
    super();
    this.state = {
      text: ""
    };

    this.handleChange = this.handleChange.bind(this);
    this.checkChar = this.checkChar.bind(this);
    this.checkLower = this.checkLower.bind(this);
    this.checkUpper = this.checkUpper.bind(this);
    this.finalCheck = this.finalCheck.bind(this);
  }

  handleChange(event) {
    this.setState({
      text: event.target.value
    });
  }

  checkChar() {
    return this.state.text.length >= 6;
  }

  checkLower() {
    let reg = /[a-z]/;
    return reg.test(this.state.text);
  }

  checkUpper() {
    let reg = /[A-Z]/;
    return reg.test(this.state.text);
  }

  finalCheck() {
    return this.checkUpper() && this.checkLower() && this.checkChar();
  }

  render() {
    return (
      <div className="app">
        <input
          type="text"
          placeholder="username"
          onChange={this.handleChange}
        />
        <div className="rules">
          <ul>
            <li className={this.checkLower() ? "passed" : "missing"}>
              1 lowercase character
            </li>
            <li className={this.checkUpper() ? "passed" : "missing"}>
              1 uppercase character
            </li>

            <li className={this.checkChar() ? "passed" : "missing"}>
              6 minimum characters
            </li>
          </ul>
        </div>
        <button disabled={this.finalCheck() ? false : true}> Submit </button>
        <footer>Made by <a href="https://twitter.com/sa_sha26" target="_blank">Sasha Tran</a></footer>
      </div>
    );
  }
}

ReactDOM.render(<PasswordChecker />, document.getElementById("container"));
View Compiled

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/react/15.4.2/react.min.js
  2. https://cdnjs.cloudflare.com/ajax/libs/react/15.4.2/react-dom.min.js