[improvement] Field: add focus method (#1987)

packages/field/en-US.md

@@ -147,6 +147,7 @@ Use ref to get field instance and call instance methods
 
 | Name | Attribute | Return value | Description |
 |------|------|------|------|
+| focus | - | - | Trigger input focus |
 | blur | - | - | Trigger input blur |
 
 ### Slot

packages/field/index.vue

@@ -127,6 +127,10 @@ export default create({
   },
 
   methods: {
+    focus() {
+      this.$refs.input && this.$refs.input.focus();
+    },
+
     blur() {
       this.$refs.input && this.$refs.input.blur();
     },

packages/field/test/index.spec.js

@@ -110,6 +110,16 @@ test('blur method', () => {
   expect(fn.mock.calls.length).toEqual(1);
 });
 
+test('focus method', () => {
+  const fn = jest.fn();
+  const wrapper = mount(Field);
+
+  wrapper.vm.$on('focus', fn);
+  wrapper.vm.focus();
+
+  expect(fn.mock.calls.length).toEqual(1);
+});
+
 test('maxlength', async() => {
   const wrapper = mount(Field, {
     attrs: {

packages/field/zh-CN.md

@@ -149,6 +149,7 @@ Field 默认支持 Input 标签所有的原生事件，如 `focus`、`blur`、`k
 
 | 方法名 | 参数 | 返回值 | 介绍 |
 |------|------|------|------|
+| focus | - | - | 获取输入框焦点 |
 | blur | - | - | 取消输入框焦点 |
 
 ### Slot