本教程操作环境：Windows10系统、react18.0.0版、Dell G3电脑。
react视图不更新怎么办？
React 数组变化不引起视图更新
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: '100%'}}
columns={this.state.columns}
data={this.state.data}
/>
<Button type="primary" onClick={this.addData.bind(this)}>添加</Button>
</div>
);
}
addData () {
let obj = {
date: '2018-05-07',
name: '小明',
address: ''
};
let data = this.state.data;
data.push(obj);
this.setState({
data: data
});
console.log(this.state);
}
}
export default App;上面代码中 通过setState设置data的值发现视图并没有更新，原因是数组的赋值是引用传递的，data = this.state.data是执行data这个数组的内存，所以执行data.push(obj)实际上相当于执行了 this.state.data.push(obj),所以react的虚拟dom发现state里面的data没有变化，所以不更新视图,而这时可以使用一个新数组：
let data = [...this.state.data];代码改为:
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: '100%'}}
columns={this.state.columns}
data={this.state.data}
/>
<Button type="primary" onClick={this.addData.bind(this)}>添加</Button>
</div>
);
}
addData () {
let obj = {
date: '2018-05-07',
name: '小明',
address: ''
};
let data = [...this.state.data];
data.push(obj);
this.setState({
data: data
});
console.log(this.state);
}
}
export default App;这样data比对以后会react会检测新旧的变化而更新dom
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