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

src/utils/index.ts

@@ -0,0 +1,28 @@
+import Vue from 'vue';
+
+export { createNamespace } from './create';
+export { suffixPx } from './format/unit';
+
+export const isServer: boolean = Vue.prototype.$isServer;
+
+export function noop() {}
+
+export function isDef(value: any): boolean {
+  return value !== undefined && value !== null;
+}
+
+export function isObj(x: any): boolean {
+  const type = typeof x;
+  return x !== null && (type === 'object' || type === 'function');
+}
+
+export function get(object: any, path: string): any {
+  const keys = path.split('.');
+  let result = object;
+
+  keys.forEach(key => {
+    result = isDef(result[key]) ? result[key] : '';
+  });
+
+  return result;
+}