build: add dev

example/dev.js

@@ -0,0 +1,13 @@
+// eslint-disable-next-line import/no-extraneous-dependencies
+import Vue from 'vue';
+
+import DatePicker from '../src/index';
+import '../src/style/index.scss';
+
+import App from './app';
+
+DatePicker.install(Vue);
+
+new Vue({
+  render: h => h(App),
+}).$mount('#app');