当项目被添加到阵列时删除占位符React

Question

我有5个职位可用数字占位符可用于添加到数组出现的项目，问题是我需要这些编号的占位符消失一旦项目已添加到阵列。

如何在项目添加到数组时删除编号的占位符？

https://codesandbox.io/s/qlp47q8j26

Hello.js

import React from 'react'; 
import update from 'immutability-helper' 
import styled from 'styled-components' 
import Product from './Product' 

const NumberWrap = styled.div` 
    display: flex; 
    flex-wrap:wrap 
    border: 1px solid #ccc; 
    flex-direction: row; 
` 

const Numbers = styled.div` 
    display:flex; 
    background: #fafafa; 
    color: #808080; 
    font-size: 32px; 
    flex: 0 0 20%; 
    min-height: 200px; 
    justify-content: center; 
    align-items:center; 
    border-right: 1px solid #ccc; 
` 

const CardWrap = styled.div` 
    display:flex; 
    flex-wrap: wrap; 
    flex-direction: row; 
    margin-top: 20px; 
` 

export default class Hello extends React.Component { 
    constructor() { 
    super() 
    this.state = { 
     placeholder: [1,2,3,4,5], 
     data: [ 
     { id: 1, header: 'Item 1'}, 
     { id: 2, header: 'Item 2'}, 
     { id: 3, header: 'Item 3'}, 
     { id: 4, header: 'Item 4'} 
     ], 
     addedItems: [], 
    } 
    } 

    handleAdd = (id) => { 
    this.setState({ 
     addedItems: update(this.state.addedItems, { 
     $push: [ 
      id, 
     ], 
     }) 
    }) 
    } 

    handleRemove = (id) => { 
    const index = this.state.addedItems.indexOf(id); 
    this.setState({ 
     addedItems: update(this.state.addedItems, { 
     $splice: [ 
      [index, 1] 
     ], 
     }) 
    }) 
    } 

    render() { 
    return(
     <div> 
     <NumberWrap> 
      { 
      this.state.placeholder.map(num => 
       <Numbers>{num} 
       { 
       this.state.data.filter(item => { 
        return this.state.addedItems.indexOf(item.id) === num - 1; 
       }).slice(0, 5).map(item => 
        <Product {...item} remove={() => { this.handleRemove(item.id) }} /> 
       ) 
       } 
       </Numbers> 
      ) 
      } 
     </NumberWrap> 


     <CardWrap> 
     { 
      this.state.data.map(item => 
      <Product 
       {...item} 
       add={()=> { 
       this.handleAdd(item.id) 
       }} 
      /> 
     )} 
     </CardWrap> 
     </div> 
    ) 
    } 
} 

Product.js

import React from "react"; 
import styled from "styled-components"; 

const Card = styled.div` 
    flex: 0 0 20%; 
    border: 1px solid #ccc; 
`; 

const Header = styled.div` 
    padding: 20px; 
`; 

const AddBtn = styled.button` 
    width:100%; 
    height: 45px; 
`; 

const Product = props => { 
    const { add, id, header, remove } = props; 
    return (
    <Card> 
     <Header key={id}> 
     {header} 
     </Header> 
     <AddBtn onClick={add}>Add</AddBtn> 
     <AddBtn onClick={remove}>Remove</AddBtn> 
    </Card> 
); 
}; 

export default Product; 

Answer 1

您应该添加添加数字数组来你的国家和渲染仅在数它不存在于这个数组中。

1. 我已将addedArray添加到构造函数中的状态。

2. 修改handleAdd和handleRemove删除并添加项目到 新阵列。

3. 添加了一个条件来渲染方法中的{num}。

这是Hello.js组件的修改后的代码：

import React from 'react'; 
import update from 'immutability-helper' 
import styled from 'styled-components' 
import Product from './Product' 

const NumberWrap = styled.div` 
    display: flex; 
    flex-wrap:wrap 
    border: 1px solid #ccc; 
    flex-direction: row; 
` 

const Numbers = styled.div` 
    display:flex; 
    background: #fafafa; 
    color: #808080; 
    font-size: 32px; 
    flex: 0 0 20%; 
    min-height: 200px; 
    justify-content: center; 
    align-items:center; 
    border-right: 1px solid #ccc; 
` 

const CardWrap = styled.div` 
    display:flex; 
    flex-wrap: wrap; 
    flex-direction: row; 
    margin-top: 20px; 
` 

export default class Hello extends React.Component { 
    constructor() { 
    super() 
    this.state = { 
     placeholder: [1,2,3,4,5], 
     addedArray: [], 
     data: [ 
     { id: 1, header: 'Item 1'}, 
     { id: 2, header: 'Item 2'}, 
     { id: 3, header: 'Item 3'}, 
     { id: 4, header: 'Item 4'} 
     ], 
     addedItems: [], 
    } 
    } 

    handleAdd = (id) => { 
    const nextAdded = [id,...this.state.addedArray]; 
    this.setState({ 
     addedArray: nextAdded, 
     addedItems: update(this.state.addedItems, { 
     $push: [ 
      id, 
     ], 
     }) 
    }) 
    } 

    handleRemove = (id) => { 
    const index = this.state.addedItems.indexOf(id); 
    const nextAdded = this.state.addedArray.filter(n => n != id); 
    this.setState({ 
     addedArray: nextAdded, 
     addedItems: update(this.state.addedItems, { 
     $splice: [ 
      [index, 1] 
     ], 
     }) 
    }) 
    } 

    render() { 
    return(
     <div> 
     <NumberWrap> 
      { 
      this.state.placeholder.map(num => 
       <Numbers> 
       {this.state.addedArray.filter(n=> n ==num).length == 0 && num} 
       { 
       this.state.data.filter(item => { 
        return this.state.addedItems.indexOf(item.id) === num - 1; 
       }).slice(0, 5).map(item => 
        <Product {...item} remove={() => { this.handleRemove(item.id) }} /> 
       ) 
       } 
       </Numbers> 
      ) 
      } 
     </NumberWrap> 


     <CardWrap> 
     { 
      this.state.data.map(item => 
      <Product 
       {...item} 
       add={()=> { 
       this.handleAdd(item.id) 
       }} 
      /> 
     )} 
     </CardWrap> 
     </div> 
    ) 
    } 
}