chore: add isFunction utils and improve isObject

src/utils/create/component.ts

@@ -2,6 +2,7 @@
  * Create a basic component with common options
  */
 import '../../locale';
+import { isFunction } from '..';
 import { camelize } from '../format/string';
 import { SlotsMixin } from '../../mixins/slots';
 import Vue, {
@@ -68,7 +69,7 @@ export function createComponent(name: string) {
   return function<Props = DefaultProps, Events = {}, Slots = {}>(
     sfc: VantComponentOptions | FunctionComponent
   ): TsxComponent<Props, Events, Slots> {
-    if (typeof sfc === 'function') {
+    if (isFunction(sfc)) {
       sfc = transformFunctionComponent(sfc);
     }
 

src/utils/create/i18n.ts

@@ -1,4 +1,4 @@
-import { get } from '..';
+import { get, isFunction } from '..';
 import { camelize } from '../format/string';
 import locale from '../../locale';
 
@@ -9,7 +9,7 @@ export function createI18N(name: string) {
     const messages = locale.messages();
     const message = get(messages, prefix + path) || get(messages, path);
 
-    return typeof message === 'function' ? message(...args) : message;
+    return isFunction(message) ? message(...args) : message;
   };
 }
 

src/utils/deep-assign.ts

@@ -1,4 +1,4 @@
-import { isDef, isObj } from '.';
+import { isDef, isObject } from '.';
 import { ObjectIndex } from './types';
 
 const { hasOwnProperty } = Object.prototype;
@@ -10,11 +10,7 @@ function assignKey(to: ObjectIndex, from: ObjectIndex, key: string) {
     return;
   }
 
-  if (
-    !hasOwnProperty.call(to, key) ||
-    !isObj(val) ||
-    typeof val === 'function'
-  ) {
+  if (!hasOwnProperty.call(to, key) || !isObject(val)) {
     to[key] = val;
   } else {
     // eslint-disable-next-line no-use-before-define

src/utils/index.ts

@@ -7,13 +7,16 @@ export const isServer: boolean = Vue.prototype.$isServer;
 
 export function noop() {}
 
-export function isDef(value: any): boolean {
-  return value !== undefined && value !== null;
+export function isDef(val: any): boolean {
+  return val !== undefined && val !== null;
 }
 
-export function isObj(x: any): boolean {
-  const type = typeof x;
-  return x !== null && (type === 'object' || type === 'function');
+export function isFunction(val: unknown): val is Function {
+  return typeof val === 'function';
+}
+
+export function isObject(val: any): val is Record<any, any> {
+  return val !== null && typeof val === 'object';
 }
 
 export function get(object: any, path: string): any {