I. Template Defects

• The greatest feature of template is that it is difficult to expand and difficult to expand. May cause logical redundancy

<Level :type="1">Ha-ha</Level>
<Level :type="2">Ha-ha</Level>
<Level :type="3">Ha-ha</Level>

Level components need to generate different labels for different type s

<template>
 <h1 v-if="type==1">
  <slot></slot>
 </h1>
 <h2 v-else-if="type==2">
  <slot></slot>
 </h2>
 <h3 v-else-if="type==3">
  <slot></slot>
 </h3>
</template>
<script>
export default {
 props: {
  type: {
   type: Number
  }
 }
};
</script>

2. Functional components

• Functional components have no templates and only render functions are allowed

export default {
 render(h) {
  return h("h" + this.type, {}, this.$slots.default);
 },
 props: {
  type: {
   type: Number
  }
 }
};

III. JSX Applications

• Using jsx makes the code look simpler and easier to read

export default {
 render(h) {
  const tag = "h" + this.type;
  return <tag>{this.$slots.default}</tag>;
 },
 props: {
  type: {
   type: Number
  }
 }
};

IV. render method custom component

• Writing List Components can automatically loop lists based on data passed in by users

<List :data="data"></List>
<script>
import List from "./components/List";
export default {
 data() {
  return { data: ["Apple", "Banana", "A mandarin orange"] };
 },
 components: {
  List
 }
};
</script>

<!-- List Component Rendering List -->
<template>
 <div class="list">
  <div v-for="(item,index) in data" :key="index">
   <li>{{item}}</li>
  </div>
 </div>
</template>
<script>
export default {
 props: {
  data: Array,
  default: () => []
 }
};
</script>

The render method is used to customize the component, and the render method is passed into the parent component.

<List :data="data" :render="render"></List>
render(h, name) {
   return <span>{name}</span>;
 }

When we need the createElement method, we think we can write a function component and pass the createElement method out.

<template>
 <div class="list">
  <div v-for="(item,index) in data" :key="index">
   <li v-if="!render">{{item}}</li>
   <!-- take render Method is passed to the function component, rendering item is passed to the component, and this is called back internally render Method -->
   <ListItem v-else :item="item" :render="render"></ListItem>
  </div>
 </div>
</template>
<script>
import ListItem from "./ListItem";
export default {
 components: {
  ListItem
 },
 props: {
  render: {
   type: Function
  },
  data: Array,
  default: () => []
 }
};
</script>

ListItem.vue calls the outermost render method to pass createElement and the current item out

<script>
export default {
 props: {
  render: {
   type: Function
  },
  item: {}
 },
 render(h) {
  return this.render(h, this.item);
 }
};
</script>

V. scope-slot

• Use v-slot to transfer internal values

<List :arr="arr">
    <template v-slot="{item}">
        {{item}}
    </template>
</List>

<div v-for="(item,key) in arr" :key="key">
    <slot :item="item"></slot>
</div>

VI. Writing Editable Forms

• Using jsx to extend to editable tables based on iview

<template>
<div>
  <Table :columns="columns" :data="data"></Table>
</div>
</template>
<script>
import Vue from 'vue';
export default {
  methods:{
    render(h,{column,index,row}){
      let value = row[column.key];
      return <div on-click={(e)=>this.changeIndex(e,index)} >
      {this.index === index? 
        <i-input type="text" value={value} on-input={(value)=>{
          this.handleChange(value,column,row)
        }} onOn-enter={()=>this.enter(row,index)}/>:
        <span>{value}</span>
      }
      </div>
    },
    enter(row,index){
      this.data.splice(index,1,row);
      this.index = -1;
    },
    handleChange(value,column,row){
      row[column['key']]= value;
    },
    changeIndex(e,index){
      this.index = index;
      this.$nextTick(()=>{
        e.currentTarget.getElementsByTagName("input")[0].focus()
      })
    }
  },
  data() {
    return {
      index:-1,
      columns: [
        {
          title: 'Name',
          key: 'name',
          render:this.render
        },
        {
          title: 'Age',
          key: 'age',
        },
        {
          title: 'Address',
          key: 'address',
        },
      ],
      data: [
        {
          name: 'John Brown',
          age: 18,
          address: 'New York No. 1 Lake Park',
          date: '2016-10-03',
        },
        {
          name: 'Jim Green',
          age: 24,
          address: 'London No. 1 Lake Park',
          date: '2016-10-01',
        },
        {
          name: 'Joe Black',
          age: 30,
          address: 'Sydney No. 1 Lake Park',
          date: '2016-10-02',
        },
        {
          name: 'Jon Snow',
          age: 26,
          address: 'Ottawa No. 2 Lake Park',
          date: '2016-10-04',
        },
      ],
    };
  },
};
</script>