[Improvement] Field: support native events (#421)

docs/markdown/en-US/field.md

@@ -90,6 +90,7 @@ Filed support all native properties of input tag，such as `maxlength`、`placeh
 | icon | Right side Icon name | `String` | - | - |
 
 ### Event
+Filed support all native events of input tag，such as `keypress`、`keyup`
 
 | Event | Description | Parameters |
 |-----------|-----------|-----------|

docs/markdown/zh-CN/field.md

@@ -92,6 +92,7 @@ Filed 默认支持 Input 标签所有的原生属性，比如 `maxlength`、`pla
 | icon | 输入框尾部图标 | `String` | - |  Icon 组件支持的类型 |
 
 ### Event
+Filed 默认支持 Input 标签所有的原生事件，比如 `keypress`、`keyup` 等
 
 | 事件名称 | 说明 | 回调参数 |
 |-----------|-----------|-----------|

packages/field/index.vue

@@ -16,23 +16,18 @@
     <textarea
       v-if="type === 'textarea'"
       v-bind="$attrs"
+      v-on="listeners"
       ref="textarea"
       class="van-field__control"
       :value="value"
-      @input="onInput"
-      @focus="$emit('focus')"
-      @blur="$emit('blur')"
     />
     <input
       v-else
       v-bind="$attrs"  
+      v-on="listeners"
       class="van-field__control"
       :type="type"
       :value="value"
-      @keypress="onKeypress"
-      @input="onInput"
-      @focus="$emit('focus')"
-      @blur="$emit('blur')"
     />
     <div
       v-if="hasIcon"
@@ -98,6 +93,14 @@ export default create({
   computed: {
     hasIcon() {
       return this.$slots.icon || this.icon;
+    },
+
+    listeners() {
+      return {
+        ...this.$listeners,
+        input: this.onInput,
+        keypress: this.onKeypress
+      };
     }
   },
 
@@ -120,6 +123,7 @@ export default create({
           event.preventDefault();
         }
       }
+      this.$emit('keypress', event);
     },
 
     adjustSize() {