CSSTransition Component

https://codesandbox.io/s/thirsty-pasteur-m77l2vp00x?from-embed=&file=/index.js

by ChrisWong

HTML

<script src="https://unpkg.com/vue@next"></script>
<div id="app">
  <div class="container" style="padding-top: 2rem">
    <transition name="alert" mode="out-in">
      <button v-if="!showAlert" @click="showAlert = true" type="button" class="btn btn-primary btn-lg">
        Show Message
      </button>

      <div v-else role="alert" class="fade alert alert-primary alert-dismissible show alert-enter-done">
        <button @click="showAlert = false" type="button" class="close">
          <span aria-hidden="true">×</span><span class="sr-only">Close alert</span>
        </button>
        <div class="alert-heading h4">Animated alert message</div>
        <p>This alert message is being transitioned in and out of the DOM.</p>
        <button @click="showAlert = false" type="button" class="btn btn-primary">
          Close
        </button>
      </div>
    </transition>
  </div>
</div>

SCSS

* {
  -webkit-text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
  --blue: #007bff;
  --indigo: #6610f2;
  --purple: #6f42c1;
  --pink: #e83e8c;
  --red: #dc3545;
  --orange: #fd7e14;
  --yellow: #ffc107;
  --green: #28a745;
  --teal: #20c997;
  --cyan: #17a2b8;
  --white: #fff;
  --gray: #6c757d;
  --gray-dark: #343a40;
  --primary: #007bff;
  --secondary: #6c757d;
  --success: #28a745;
  --info: #17a2b8;
  --warning: #ffc107;
  --danger: #dc3545;
  --light: #f8f9fa;
  --dark: #343a40;
  --breakpoint-xs: 0;
  --breakpoint-sm: 576px;
  --breakpoint-md: 768px;
  --breakpoint-lg: 992px;
  --breakpoint-xl: 1200px;
  --font-family-sans-serif: -apple-system, BlinkMacSystemFont, "Segoe UI",
    Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif,
    "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
  --font-family-monospace: SFMono-Regular, Menlo, Monaco, Consolas,
    "Liberation Mono", "Courier New", monospace;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
    "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji",
    "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
}
button {
  font: 400 13.3333px Arial;
}

.container {
  width: 100%;
  max-width: 1140px;
  padding-right: 15px;
  padding-left: 15px;
  margin-right: auto;
  margin-left: auto;
}
.alert {
  position: relative;
  padding: 0.75rem 1.25rem;
  margin-bottom: 1rem;
  border: 1px solid transparent;
  border-radius: 0.25rem;
}

.alert-primary {
  color: #004085;
  background-color: #cce5ff;
  border-color: #b8daff;
}
.alert-dismissible .close {
  position: absolute;
  top: 0;
  right: 0;
  padding: 0.75rem 1.25rem;
  color: inherit;
}

.alert-heading {
  text-align: left;
  box-sizing: border-box;
  margin-bottom: 0.5rem;
  font-weight: 500;
  line-height: 1.2;
  font-size: 1.5rem;
  color: inherit;
}

.btn {
  -webkit-text-size-adjust: 100%;
  -webkit-tap-highlight-color: transparent;
  --blue: #007bff;
 ...

JavaScript

const app = Vue.createApp({
  data() {
    return {
      showAlert: false,
    }
  }
});

app.mount('#app');