<div id="app">
	<h2> Password Strength</h2>

	<div class="input_container">
		<ul>
			<li v-bind:class="{ is_valid: contains_eight_characters }">8 Characters</li>
			<li v-bind:class="{ is_valid: contains_number }">Contains Number</li>
			<li v-bind:class="{ is_valid: contains_uppercase }">Contains Uppercase</li>
			<li v-bind:class="{ is_valid: contains_special_character }">Contains Special Character</li>
		</ul>

		<div class="checkmark_container" v-bind:class="{ show_checkmark: valid_password }">		
			<svg width="50%" height="50%" viewBox="0 0 140 100">
				<path class="checkmark" v-bind:class="{ checked: valid_password }" d="M10,50 l25,40 l95,-70" />
			</svg>
		</div>
		
    <input type="password" @input="checkPassword" v-model="password" autocomplete="off" placeholder="Password" />
	</div>
</div>
/* Basic Config --------- */

html { box-sizing: border-box; }

*, *:before, *:after { box-sizing: inherit; }

html, body {
	height: 100%;
	width: 100%;
	margin: 0;
	padding: 0;
}

body {
	font-family: 'Open Sans', sans-serif;
	display: flex;
	justify-content: center;
	align-items: center;
	background: #ff6b6b;
	-webkit-font-smoothing: antialiased;
	-moz-osx-font-smoothing: grayscale;
}

h2 {
	text-align: center;
	color: #FFF;
	font-weight: 400;
}

ul {
	padding-left: 20px;
	display: flex;
	flex-direction: column;
	align-items: flex-start;
}

li { 
	margin-bottom: 8px;
	color: #525f7f;
	position: relative;
}

li:before {
  content: "";
	width: 0%; height: 2px;
	background: #2ecc71;
	position: absolute;
	left: 0; top: 50%;
	display: block;
	transition: all .6s cubic-bezier(0.175, 0.885, 0.32, 1.275);
}

#app { width: 400px; }


/* Password Input --------- */

.input_container {
	position: relative;
	padding: 30px;
	box-shadow: 0 10px 20px rgba(0,0,0,0.19), 0 6px 6px rgba(0,0,0,0.23);
	border-radius: 6px;
	background: #FFF;
}

input[type="password"] {
	line-height: 1.5;
	display: block;
	color: rgba(136, 152, 170, 1);
	font-weight: 300;
	width: 100%;
	height: calc(2.75rem + 2px);
	padding: .625rem .75rem;
	border-radius: .25rem;
	background-color: #fff;
	transition: border-color .4s ease;
	border: 1px solid #cad1d7;
	outline: 0;
}

input[type="password"]:focus {
	border-color: rgba(50, 151, 211, .45);
}


/* Checkmark & Strikethrough --------- */

.is_valid { color: rgba(136, 152, 170, 0.8); }
.is_valid:before { width: 100%; }

.checkmark_container {
	border-radius: 50%;
	position: absolute;
	top: -15px; right: -15px;
	background: #2ecc71;
	width: 50px; height: 50px;
	visibility: hidden;
	opacity: 0;
	display: flex;
	justify-content: center;
	align-items: center;
	transition: opacity .4s ease;
}

.show_checkmark {
  visibility: visible;
  opacity: 1;
}

.checkmark {
  width: 100%;
  height: 100%;
  fill: none;
  stroke: white;
  stroke-width: 15;
  stroke-linecap: round;
  stroke-dasharray: 180;
  stroke-dashoffset: 180;
}

.checked { animation: draw 0.5s ease forwards; }

@keyframes draw {
  to { stroke-dashoffset: 0; }
}
// MESS

const App = new Vue({
  el: "#app",
  data: {
    password: null,
    password_length: 0,
		contains_eight_characters: false,
    contains_number: false,
    contains_uppercase: false,
		contains_special_character: false,
    valid_password: false
  },
  
  methods: {
    checkPassword() {
      this.password_length = this.password.length;
			const format = /[ !@#$%^&*()_+\-=\[\]{};':"\\|,.<>\/?]/;
			
      if (this.password_length > 8) {
        this.contains_eight_characters = true;
      } else {
        this.contains_eight_characters = false;
			}
			
      this.contains_number = /\d/.test(this.password);
      this.contains_uppercase = /[A-Z]/.test(this.password);
			this.contains_special_character = format.test(this.password);
      
      if (this.contains_eight_characters === true &&
					this.contains_special_character === true &&
					this.contains_uppercase === true &&
					this.contains_number === true) {
						this.valid_password = true;			
      } else {
        this.valid_password = false;
      }
    }
  }
});
View Compiled

External CSS

  1. https://fonts.googleapis.com/css?family=Open+Sans:300,400,600

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.min.js