react視圖不更新怎麼辦

react視圖不更新是因為陣列的賦值是引用傳遞的，其解決方案：1、開啟對應的react檔案；2、透過使用「let data = [...this.state.data] ;”新數組方式實現視圖更新即可。

本教學操作環境：Windows10系統、react18.0.0版、Dell G3電腦。

react視圖不更新怎麼辦？

React 陣列變更不會造成視圖更新

import React, { Component } from 'react';
import './App.css';
import Todo from './components/todo/index'
import { Table, Button } from 'element-react';
class App extends Component {
  constructor(props) {
    super(props);
    this.state = {
      columns: [
        {
          label: "日期",
          prop: "date",
          width: 180
        },
        {
          label: "姓名",
          prop: "name",
          width: 180
        },
        {
          label: "地址",
          prop: "address"
        }
      ],
      data: [{
        date: '2016-05-02',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1518 弄'
      }, {
        date: '2016-05-04',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1517 弄'
      }, {
        date: '2016-05-01',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1519 弄'
      }, {
        date: '2016-05-03',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1516 弄'
      },{
        date: '2016-05-02',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1518 弄'
      }, {
        date: '2016-05-04',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1517 弄'
      }, {
        date: '2016-05-01',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1519 弄'
      }, {
        date: '2016-05-03',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1516 弄'
      }]
    }
  }
  render() {
    return (
     <div>
       <Todo list={this.state.data}/>
       <Table
           style={{width: &#39;100%&#39;}}
           columns={this.state.columns}
           data={this.state.data}
       />
       <Button type="primary" onClick={this.addData.bind(this)}>添加</Button>
     </div>
    );
  }
  addData () {
    let obj = {
      date: &#39;2018-05-07&#39;,
      name: &#39;小明&#39;,
      address: &#39;&#39;
    };
    let data = this.state.data;
    data.push(obj);
    this.setState({
      data: data
    });
    console.log(this.state);
  }
}
export default App;

上面程式碼中透過setState設定data的值發現視圖並沒有更新，原因是陣列的賦值是引用傳遞的，data = this.state.data是執行data這個數組的內存，所以執行data.push(obj)實際上相當於執行了this.state.data.push(obj),所以react的虛擬dom發現state裡面的data沒有變化，所以不更新視圖,而這時可以使用一個新數組：

 let data = [...this.state.data];

代碼改為:

import React, { Component } from 'react';
import './App.css';
import Todo from './components/todo/index'
import { Table, Button } from 'element-react';
class App extends Component {
  constructor(props) {
    super(props);
    this.state = {
      columns: [
        {
          label: "日期",
          prop: "date",
          width: 180
        },
        {
          label: "姓名",
          prop: "name",
          width: 180
        },
        {
          label: "地址",
          prop: "address"
        }
      ],
      data: [{
        date: '2016-05-02',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1518 弄'
      }, {
        date: '2016-05-04',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1517 弄'
      }, {
        date: '2016-05-01',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1519 弄'
      }, {
        date: '2016-05-03',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1516 弄'
      },{
        date: '2016-05-02',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1518 弄'
      }, {
        date: '2016-05-04',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1517 弄'
      }, {
        date: '2016-05-01',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1519 弄'
      }, {
        date: '2016-05-03',
        name: '王小虎',
        address: '上海市普陀区金沙江路 1516 弄'
      }]
    }
  }
  render() {
    return (
     <div>
       <Todo list={this.state.data}/>
       <Table
           style={{width: &#39;100%&#39;}}
           columns={this.state.columns}
           data={this.state.data}
       />
       <Button type="primary" onClick={this.addData.bind(this)}>添加</Button>
     </div>
    );
  }
  addData () {
    let obj = {
      date: &#39;2018-05-07&#39;,
      name: &#39;小明&#39;,
      address: &#39;&#39;
    };
    let data = [...this.state.data];
    data.push(obj);
    this.setState({
      data: data
    });
    console.log(this.state);
  }
}
export default App;

這樣data比對以後會react會檢測新舊的變化而更新dom

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