Add mixin for migration of components

src/mixins/migrating.js

@@ -0,0 +1,60 @@
+/**
+ * Show migrating guide in browser console.
+ *
+ * Usage:
+ * import Migrating from 'element-ui/src/mixins/migrating';
+ *
+ * mixins: [Migrating]
+ *
+ * add getMigratingConfig method for your component.
+ *  getMigratingConfig() {
+ *    return {
+ *      props: {
+ *        'allow-no-selection': 'allow-no-selection is removed.',
+ *        'selection-mode': 'selection-mode is removed.'
+ *      },
+ *      events: {
+ *        selectionchange: 'selectionchange is renamed to selection-change.'
+ *      }
+ *    };
+ *  },
+ */
+export default {
+  mounted() {
+    if (process.env.NODE_ENV === 'production') return;
+    if (!this.$vnode) return;
+    const { props = {}, events = {} } = this.getMigratingConfig();
+    const { data, componentOptions } = this.$vnode;
+    const definedProps = data.attrs || {};
+    const definedEvents = componentOptions.listeners || {};
+
+    for (let propName in definedProps) {
+      if (definedProps.hasOwnProperty(propName) && props[propName]) {
+        console.warn(
+          `[Element Migrating][${this.$options.name}][Attribute]: ${
+            props[propName]
+          }`
+        );
+      }
+    }
+
+    for (let eventName in definedEvents) {
+      if (definedEvents.hasOwnProperty(eventName) && events[eventName]) {
+        console.warn(
+          `[Element Migrating][${this.$options.name}][Event]: ${
+            events[eventName]
+          }`
+        );
+      }
+    }
+  },
+
+  methods: {
+    getMigratingConfig() {
+      return {
+        props: {},
+        events: {},
+      };
+    },
+  },
+};