Vue

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.5/css/select2.min.css">
<script src="https://cdnjs.cloudflare.com/ajax/libs/select2/4.0.5/js/select2.min.js"></script>
<div id="app">
  <bs-select :value="test" v-on:change-value="test = $event" :options="options"></bs-select>
  <br><br>
  {{ test }}
  
  <br><br>
  
  <button @click="test = 'bug'">
  Set 'test' variable to 'bug'
  </button>
</div>

<div>
Event is firing twice in console...
</div>

CSS

* {
  font-family: Arial;
}

div {
  margin: 20px;
}

Vue

Vue.component("bs-select",{
template:
 `<select :value="value" v-on:change="changeVal" style="width: 100%">
    <option value="" selected disabled>Choose...</option>
    <option v-if="!options">{{ value }}</option>
    <option v-for="option in options" :value="option.value">{{ option.text }}</option>
  </select>`,
  props: ["value", "options"],
  methods: {
  	changeVal: function(event) {
    	this.$emit('change-value', event.target.value)
    }
  }
});

new Vue({
  el: "#app",
  data: {
    test: "bug",
    options: [
    {
      value: "hello",
      text: "Hello"
    },
    {
      value: "bug",
      text: "Bug"
    }
    ]
  }
})