[new feature] Field: add error-message prop (#492)

packages/field/index.vue

@@ -30,6 +30,11 @@
       :type="type"
       :value="value"
     >
+    <div
+      v-if="errorMessage"
+      v-text="errorMessage"
+      class="van-field__error-message"
+    />
     <div
       v-if="hasIcon"
       v-show="$slots.icon || value"
@@ -68,6 +73,7 @@ export default create({
     border: Boolean,
     required: Boolean,
     autosize: Boolean,
+    errorMessage: String,
     onIconClick: {
       type: Function,
       default: () => {}

packages/vant-css/src/field.css

@@ -22,6 +22,12 @@
     padding-left: 90px;
   }
 
+  &__error-message {
+    color: $red;
+    font-size: 12px;
+    text-align: left;
+  }
+
   &--has-textarea {
     .van-field__control {
       min-height: 60px;