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

src/utils/deep-assign.ts

@@ -0,0 +1,27 @@
+/* eslint-disable no-use-before-define */
+import { isDef, isObj } from '.';
+import { ObjectIndex } from './types';
+
+const { hasOwnProperty } = Object.prototype;
+
+function assignKey(to: ObjectIndex, from: ObjectIndex, key: string) {
+  const val = from[key];
+
+  if (!isDef(val)) {
+    return;
+  }
+
+  if (!hasOwnProperty.call(to, key) || !isObj(val) || typeof val === 'function') {
+    to[key] = val;
+  } else {
+    to[key] = deepAssign(Object(to[key]), from[key]);
+  }
+}
+
+export function deepAssign(to: ObjectIndex, from: ObjectIndex): ObjectIndex {
+  Object.keys(from).forEach(key => {
+    assignKey(to, from, key);
+  });
+
+  return to;
+}