6. 弹出框组件 Example> 使用到的特性：组件，prop 传递，内容插入 (content insertion)

使用到的特性：组件，prop 传递，内容插入 (content insertion)，过渡 (transitions)。

<!DOCTYPE html>
<html>
  <head>
    <title>Modal Component</title>
    <script src="https://unpkg.com/vue@2"></script>
    <link rel="stylesheet" type="text/css" href="./style.css" />
    <!-- template for the modal component -->
    <script type="text/x-template" id="modal-template">
      <transition name="modal">
        <div class="modal-mask">
          <div class="modal-wrapper">
            <div class="modal-container">

              <div class="modal-header">
                <slot name="header">
                  default header
                </slot>
              </div>

              <div class="modal-body">
                <slot name="body">
                  default body
                </slot>
              </div>

              <div class="modal-footer">
                <slot name="footer">
                  default footer
                  <button class="modal-default-button" @click="$emit('close')">
                    OK
                  </button>
                </slot>
              </div>
            </div>
          </div>
        </div>
      </transition>
    </script>
  </head>
  <body>
    <!-- app -->
    <div id="app">
      <button id="show-modal" @click="showModal = true">Show Modal</button>
      <!-- use the modal component, pass in the prop -->
      <modal v-if="showModal" @close="showModal = false">
        <!--
      you can use custom content here to overwrite
      default content
    -->
        <h3 slot="header">custom header</h3>
      </modal>
    </div>

    <script>
      // register modal component
      Vue.component("modal", {
        template: "#modal-template"
      });

      // start app
      new Vue({
        el: "#app",
        data: {
          showModal: false
        }
      });
    </script>
  </body>
</html>

/* ./style.css */
.modal-mask {
  position: fixed;
  z-index: 9998;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5);
  display: table;
  transition: opacity 0.3s ease;
}

.modal-wrapper {
  display: table-cell;
  vertical-align: middle;
}

.modal-container {
  width: 300px;
  margin: 0px auto;
  padding: 20px 30px;
  background-color: #fff;
  border-radius: 2px;
  box-shadow: 0 2px 8px rgba(0, 0, 0, 0.33);
  transition: all 0.3s ease;
  font-family: Helvetica, Arial, sans-serif;
}

.modal-header h3 {
  margin-top: 0;
  color: #42b983;
}

.modal-body {
  margin: 20px 0;
}

.modal-default-button {
  float: right;
}

/*
 * The following styles are auto-applied to elements with
 * transition="modal" when their visibility is toggled
 * by Vue.js.
 *
 * You can easily play with the modal transition by editing
 * these styles.
 */

.modal-enter {
  opacity: 0;
}

.modal-leave-active {
  opacity: 0;
}

.modal-enter .modal-container,
.modal-leave-active .modal-container {
  -webkit-transform: scale(1.1);
  transform: scale(1.1);
}