feat(Cascader): add placeholder attr

src/cascader/README.en-US.md

@@ -5,12 +5,13 @@
 
 name | type | default | description | required
 -- | -- | -- | -- | --
-close-btn | Boolean / Slot | true | \- | N
-keys | Object | - | Typescript：`KeysType` | N
+close-btn | Boolean / Slot | true | [see more ts definition](https://github.com/Tencent/tdesign-miniprogram/blob/develop/src/common/common.ts) | N
+keys | Object | - | Typescript：`KeysType`。[see more ts definition](https://github.com/Tencent/tdesign-miniprogram/blob/develop/src/common/common.ts) | N
 options | Array | [] | Typescript：`Array<CascaderOption>` | N
+placeholder | String | 选择选项 | \- | N
 sub-titles | Array | [] | Typescript：`Array<string>` | N
-theme | String | step | options：step/tab | N
-title | String / Slot | - | \- | N
+theme | String | step | options: step/tab | N
+title | String / Slot | - | [see more ts definition](https://github.com/Tencent/tdesign-miniprogram/blob/develop/src/common/common.ts) | N
 value | String / Number | null | \- | N
 default-value | String / Number | undefined | uncontrolled property | N
 visible | Boolean | false | \- | N

src/cascader/README.md

@@ -51,12 +51,13 @@ isComponent: true
 
 名称 | 类型 | 默认值 | 说明 | 必传
 -- | -- | -- | -- | --
-close-btn | Boolean / Slot | true | 关闭按钮 | N
-keys | Object | - | 用来定义 value / label 在 `options` 中对应的字段别名。TS 类型：`KeysType` | N
+close-btn | Boolean / Slot | true | 关闭按钮。[通用类型定义](https://github.com/Tencent/tdesign-miniprogram/blob/develop/src/common/common.ts) | N
+keys | Object | - | 用来定义 value / label 在 `options` 中对应的字段别名。TS 类型：`KeysType`。[通用类型定义](https://github.com/Tencent/tdesign-miniprogram/blob/develop/src/common/common.ts) | N
 options | Array | [] | 可选项数据源。TS 类型：`Array<CascaderOption>` | N
+placeholder | String | 选择选项 | 未选中时的提示文案 | N
 sub-titles | Array | [] | 每级展示的次标题。TS 类型：`Array<string>` | N
 theme | String | step | 展示风格。可选项：step/tab | N
-title | String / Slot | - | 标题 | N
+title | String / Slot | - | 标题。[通用类型定义](https://github.com/Tencent/tdesign-miniprogram/blob/develop/src/common/common.ts) | N
 value | String / Number | null | 选项值 | N
 default-value | String / Number | undefined | 选项值。非受控属性 | N
 visible | Boolean | false | 是否展示 | N

src/cascader/__test__/__snapshots__/demo.test.js.snap

@@ -347,6 +347,7 @@ exports[`Cascader Cascader keys demo works fine 1`] = `
         },
       ]
     }}"
+    placeholder="未选中时的提示文案"
     title="请选择地址"
     visible="{{false}}"
     bind:change="onChange"

src/cascader/_example/keys/index.wxml

@@ -6,5 +6,6 @@
   keys="{{keys}}"
   options="{{options}}"
   title="请选择地址"
+  placeholder="未选中时的提示文案"
   bind:change="onChange"
 ></t-cascader>

src/cascader/cascader.ts

@@ -11,7 +11,6 @@ export interface CascaderProps extends TdCascaderProps {}
 
 type OptionsType = TdCascaderProps['options']['value'];
 
-const defaultOptionLabel = '选择选项';
 @wxComponent()
 export default class Cascader extends SuperComponent {
   externalClasses = [`${prefix}-class`];
@@ -35,9 +34,8 @@ export default class Cascader extends SuperComponent {
     stepIndex: 0,
     selectedIndexes: [],
     selectedValue: [],
-    defaultOptionLabel,
     scrollTopList: [],
-    steps: [defaultOptionLabel],
+    steps: [],
   };
 
   observers = {
@@ -56,7 +54,7 @@ export default class Cascader extends SuperComponent {
     },
 
     'selectedIndexes, options'() {
-      const { options, selectedIndexes, keys } = this.data;
+      const { options, selectedIndexes, keys, placeholder } = this.data;
       const selectedValue = [];
       const steps = [];
       const items = [options];
@@ -76,7 +74,7 @@ export default class Cascader extends SuperComponent {
       }
 
       if (steps.length < items.length) {
-        steps.push(defaultOptionLabel);
+        steps.push(placeholder);
       }
 
       this.setData({

src/cascader/cascader.wxml

@@ -15,7 +15,7 @@
         <view wx:if="{{theme == 'step'}}" class="{{name}}__steps">
           <view wx:for="{{steps}}" wx:key="index" class="{{name}}__step" bind:tap="onStepClick" data-index="{{index}}">
             <view
-              class="{{name}}__step-dot {{name}}__step-dot--{{item !== defaultOptionLabel ? 'active' : ''}} {{name}}__step-dot--{{index === steps.length - 1 ? 'last' : ''}}"
+              class="{{name}}__step-dot {{name}}__step-dot--{{item !== placeholder ? 'active' : ''}} {{name}}__step-dot--{{index === steps.length - 1 ? 'last' : ''}}"
             ></view>
             <view class="{{name}}__step-label {{name}}__step-label--{{index === stepIndex ? 'active' : ''}}">
               {{ item }}

src/cascader/props.ts

@@ -20,6 +20,11 @@ const props: TdCascaderProps = {
     type: Array,
     value: [],
   },
+  /** 未选中时的提示文案 */
+  placeholder: {
+    type: String,
+    value: '选择选项',
+  },
   /** 每级展示的次标题 */
   subTitles: {
     type: Array,

src/cascader/type.ts

@@ -30,6 +30,14 @@ export interface TdCascaderProps<CascaderOption extends TreeOptionData = TreeOpt
     type: ArrayConstructor;
     value?: Array<CascaderOption>;
   };
+  /**
+   * 未选中时的提示文案
+   * @default 选择选项
+   */
+  placeholder?: {
+    type: StringConstructor;
+    value?: string;
+  };
   /**
    * 每级展示的次标题
    * @default []