[improvement] Area: optimize performance (#1055)

packages/area/index.less

@@ -57,11 +57,10 @@
 
     &__item {
       padding: 0 5px;
-      color: @gray-dark;
+      color: @text-color;
 
       &--selected {
         font-weight: 500;
-        color: @text-color;
       }
 
       &--disabled {

packages/area/index.ts

@@ -33,13 +33,6 @@ VantComponent({
     columns: []
   },
 
-  computed: {
-    displayColumns() {
-      const { columns = [], columnsNum } = this.data;
-      return columns.slice(0, +columnsNum);
-    }
-  },
-
   watch: {
     value(value) {
       this.code = value;
@@ -68,7 +61,8 @@ VantComponent({
 
     onChange(event: Weapp.Event) {
       const { value } = event.detail;
-      const { pickerValue, displayColumns } = this.data;
+      const { pickerValue } = this.data;
+      const displayColumns = this.getDisplayColumns();
       const index = pickerValue.findIndex(
         (item, index) => item !== value[index]
       );
@@ -159,7 +153,8 @@ VantComponent({
     },
 
     getValues() {
-      const { displayColumns = [], pickerValue = [] } = this.data;
+      const { pickerValue = [] } = this.data;
+      const displayColumns = this.getDisplayColumns();
       return displayColumns
         .map((option, index) => option[pickerValue[index]])
         .filter(value => !!value);
@@ -201,6 +196,11 @@ VantComponent({
     reset() {
       this.code = '';
       this.setValues();
+    },
+
+    getDisplayColumns() {
+      const { columns = [], columnsNum } = this.data;
+      return columns.slice(0, +columnsNum);
     }
   }
 });

packages/area/index.wxml

@@ -17,7 +17,8 @@
     class="van-picker__columns"
   >
     <picker-view-column
-      wx:for="{{ displayColumns }}"
+      wx:if="{{ rowIndex < columnsNum }}"
+      wx:for="{{ columns }}"
       wx:for-item="row"
       wx:for-index="rowIndex"
       wx:key="rowIndex"

packages/wxs/array.wxs

@@ -1,5 +1,5 @@
-function isArray(obj) {
-  return obj && obj.constructor === 'Array';
+function isArray(array) {
+  return array && array.constructor === 'Array';
 }
 
 module.exports.isArray = isArray;