//for development
<script src="https://cdn.jsdelivr.net/npm/vue@2.6.14/dist/vue.js"></script>
//for production
<script src="https://cdn.jsdelivr.net/npm/vue@2.6.14"></script>
//vue 3 https://vuejs.org/guide/quick-start.html#without-build-tools
<script src="https://unpkg.com/vue@3"></script>
<script src="https://cdn.jsdelivr.net/npm/vue@2.6.12/dist/vue.js"></script><script src="https://unpkg.com/vue/dist/vue.js"></script><script src="https://unpkg.com/vue@3"></script><script src="https://cdn.jsdelivr.net/npm/vue@2.6.14/dist/vue.js"></script><script src="https://cdn.jsdelivr.net/npm/vue@2.6.14/dist/vue.min.js"></script>
<script src="https://unpkg.com/vue@2.6.14/dist/vue.min.js"></script>