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Custom select drop-down option box component in WeChat applet

hzc
hzc forward
2020-06-24 10:10:07 4111browse

Knowledge points:Component,animation,Get the index and content of the currently clicked element

WeChat Mini There is no select drop-down option box in the program, so there is only customization. If you want to customize, you can choose thetemplatemethod, or you can choose thecomponentmethod to create it.

This time I chose components, so that I only need to introduce components and add data, and don’t worry about other things, so that it can be reused in multiple places.

Step 1: Create the files required for the component

I like to put all shared content at the same level as the pages file , so we have the following directory structure

  1. First create a folder with a custom name, such as my Componet

  2. above
  3. Create another select folder, then: right-click this folder and create the following Component. Then enter the name that needs to be created. I took the name of select here for convenience. Then 4 files, js, json, wxml, and wxss will be created automatically.

##Step 2: Start configuring components

Note:If you created it through the first step, you can skip the second step directly.

    The component folder created in the first step has been automatically configured. Just
  1. when introducing the component

    , configure the name and location of the component in the json file of the page where the component is introduced.

  2. If you manually create the js, json, wxml, and wxss files of the component, you need to fill in the json file
  3. "component":truerepresents a custom component declaration. The js file also needs to be written in this format:

    Component({ properties: { // 这里定义了innerText属性,属性值可以在组件使用时指定 innerText: { type: String, value: 'default value', } }, data: { // 这里是一些组件内部数据 someData: {} }, methods: { // 这里是一个自定义方法 customMethod: function(){} } })

Step 3: Customize the component style and js.

Note:You can put the component location inpagesofapp.jsonPut the page in the first place, so that you can write code on the component page. For example, my directory structure above: it needs to be written as"Component/select/select",followed by other pages. This is much more convenient.

1. Component wxml
  {{nowText}}    {{item.text}} 

    (1)
  1. animation="{{animationData}}"This is the animation effect of the down arrow

  2. (2)
  3. data-index="{{index}}"This is the index of the current element when it is clicked

  4. (3) selectToggle is an event that imitates the hiding and display of the drop-down option box.
  5. (4) setText is an event that sets the content after imitating the drop-down option box to select a sub-item.
  6. (5) selectShow indicates whether the option option is displayed

2. wxss of the component

.com-selectBox{ width: 200px; }.com-sContent{ border: 1px solid #e2e2e2; background: white; font-size: 16px; position: relative; height: 30px; line-height: 30px; }.com-sImg{ position: absolute; right: 10px; top: 11px; width: 16px; height: 9px; transition: all .3s ease; }.com-sTxt{ overflow: hidden; text-overflow: ellipsis; white-space: nowrap; padding:0 20px 0 6px; font-size: 14px; }.com-sList{ background: white; width: inherit; position: absolute; border: 1px solid #e2e2e2; border-top: none; box-sizing: border-box; z-index: 3; max-height: 120px; overflow: auto; }.com-sItem{ height: 30px; line-height: 30px; border-top: 1px solid #e2e2e2; padding: 0 6px; text-align: left; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-size: 14px; }.com-sItem:first-child{ border-top: none; }

3. Component’s js
// Componet/Componet.jsComponent({ /** * 组件的属性列表 */ properties: { propArray:{ type:Array, } }, /** * 组件的初始数据 */ data: { selectShow:false,//初始option不显示 nowText:"请选择",//初始内容 animationData:{}//右边箭头的动画 }, /** * 组件的方法列表 */ methods: {    //option的显示与否 selectToggle:function(){ var nowShow=this.data.selectShow;//获取当前option显示的状态 //创建动画 var animation = wx.createAnimation({ timingFunction:"ease" }) this.animation=animation; if(nowShow){ animation.rotate(0).step(); this.setData({ animationData: animation.export() }) }else{ animation.rotate(180).step(); this.setData({ animationData: animation.export() }) } this.setData({ selectShow: !nowShow }) }, //设置内容 setText:function(e){ var nowData = this.properties.propArray;//当前option的数据是引入组件的页面传过来的,所以这里获取数据只有通过this.properties var nowIdx = e.target.dataset.index;//当前点击的索引 var nowText = nowData[nowIdx].text;//当前点击的内容 //再次执行动画,注意这里一定,一定,一定是this.animation来使用动画 this.animation.rotate(0).step(); this.setData({ selectShow: false, nowText:nowText, animationData: this.animation.export() }) } } })

    (1) Component’s
  1. properties

    Attribute is an external attribute. What I understand is that it can be used as data. It is an object with three attributes, namelytypeindicating the attribute type,valuerepresents the initial value of the attribute,observerrepresents the response function when the attribute value is changed.typeis required, others are optional. If there is onlytype, it can be written as:Attribute name: type type.

  2. (2) The data of the component is the same as the data of the ordinary page. It is the internal data of the component and is used for the component together with
  3. propertiesTemplate rendering.

  4. (3) 组件的 method 是专门用于 事件响应函数 和 任意的自定义方法。在这里面获取数据有两种方法:一种是获取data里的数据:this.data.属性名;一种是获取 properties 中的属性值:this.properties.属性名

  5. (4) 创建animation动画,作用在通过 true 和 false 切换显示状态的内容上没有过渡、没有过渡、没有过渡

第四步:引入组件,传入组件所需数据

1. 引入前,需要在引入组件的页面的json文件中配置,比如我要在 index.wxml 中引入,那么在 index.json 中我就需要配置:

"usingComponents": { "Select": "/Componet/select/select"}
  1. (1)Select是你定义的组件的名称,后面的是组件所在的位置。 / 单斜杠表示根目录,是绝对路径。

  2. (2) 如果出现下面这种说没找到路径的,一定是自己填写的路径不对,认真查找。

2.配置好后,就可以引入组件。

(1) prop-array 是我自定义的属性名,这个是和组件所在的 js 中properties中的属性是对应的。在properties定义的属性中,属性名采用驼峰写法(例如:propArray);在引入组件的wxml中,指定属性值时则对应使用连字符写法(例如:prop-array="...")。

3.最后就是传入数据了。在引入组件的js的data中,添加:

selectArray: [{ "id": "10", "text": "会计类"}, { "id": "21", "text": "工程类"}]

最终结果:

如果引入两个相同的组件,传入的数据也相同:


这样的方式组件并不会相互影响,都是独立的。

对了,组件样式的规则可以查看官方的规则

第五步:获取点击的内容,即组件间的通信

效果有了,最关键的是获取选中的内容。这个怎么实现呢,这时候需要组建间通信与事件了。

1. 对组件的事件进行监听:

(1) 这里myget是自定义的子组件需要触发的事件名,getDate是引入组件的页面需要获取传过来的数据的自定义的事件名。

2. 子组件触发事件

因为这里的select组件是点击下拉列表的内容才进行内容的更新,所以这里只需要在下拉列表里添加一个点击事件,而原来已经设置了setText事件。所以只需要在setText函数里面写触发事件就行了。

在setText函数的内容里加上:

var nowDate={ id:nowIdx, text:nowText }this.triggerEvent('myget', nowDate)
  1. (1) 这里的 myget 和 bind:myget ,名称一定要对应。

  2. (2) nowDate是需要传回的数据,不一定要弄成对象,想传什么传什么,我这里只是演示而已。我试了一下也可以传函数。。。

3. 引入组件的页面的js

添加引入组件时,自定义的函数:

getDate:function(e){ console.log(e.detail) }

e的内容为:

传过来的值就在detail里面。

到此,一个完整的select组件就完成了。

更新:

如果要select组件默认显示传入的第一个数据,做法是:

  1. (1) 在select组件的wxml页面,在class为com-sTxt的view标签中,原来的 {{ nowText }} 改为 {{ nowText==' ' ? propArray[0].text : nowText }}。

  2. (2) 然后在 select 组件 js文件 中原来nowText的值修改为 ‘ ’ 空。

  3. (3) 这样的话就表示如果最初nowText为空,就显示传入数据的第一个值,否则就是选中的值

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