[improvement] rename packages dir to src (#3659)

src/mixins/click-outside.js

@@ -0,0 +1,20 @@
+/**
+ * Listen to click outside event
+ */
+import { on, off } from '../utils/dom/event';
+
+export const ClickOutsideMixin = config => ({
+  mounted() {
+    this.clickOutsideHandler = event => {
+      if (!this.$el.contains(event.target)) {
+        this[config.method]();
+      }
+    };
+
+    on(document, config.event, this.clickOutsideHandler);
+  },
+
+  beforeDestroy() {
+    off(document, config.event, this.clickOutsideHandler);
+  }
+});