在reactjs中设置状态时出现问题
我有一个非常简单的代码来设置一个状态变量,但有麻烦 我看到this.state.chart_选项显示在控制台上,但为空 代码:\u在reactjs中设置状态时出现问题,reactjs,Reactjs,我有一个非常简单的代码来设置一个状态变量,但有麻烦 我看到this.state.chart_选项显示在控制台上,但为空 代码:\u import React from "react"; import { render } from "react-dom"; // Import Highcharts import Highcharts from "highcharts/highstock"; import drilldow from "highcharts/modules/drilldown";
import React from "react";
import { render } from "react-dom";
// Import Highcharts
import Highcharts from "highcharts/highstock";
import drilldow from "highcharts/modules/drilldown";
//import HighchartsReact from "./HighchartsReact.js";
import PieChart from "highcharts-react-official";
drilldow(Highcharts);
const options = {
chart: {
type: "pie"
},
series: [
{
data: [{ y: 100, name: "Female" }, { y: 50, name: "Male" }]
}
]
};
class App extends React.Component {
constructor() {
super();
this.state = {
chart_options: null
};
this.setState({ chart_options: options }, () => {
console.log("this.state - ", this.state);
console.log("options - ", options);
});
}
onFilterClickHandler = () => {
console.log("hi", this.state.chart_options);
};
render() {
const key = 1;
return (
<div>
<div>
<label>
<input
type="checkbox"
value={key}
onClick={this.onFilterClickHandler}
/>
</label>
</div>
<h2>Highcharts</h2>
<PieChart highcharts={Highcharts} options={options} />
</div>
);
}
}
render(<App />, document.getElementById("root"));
从“React”导入React;
从“react dom”导入{render};
//导入海图
从“Highcharts/highstock”导入Highcharts;
从“highcharts/modules/drilldown”导入drilldow;
//从“/HighchartsReact.js”导入HighchartsReact;
从“highcharts react official”导入PieChart;
钻井道(海图);
常量选项={
图表:{
类型:“馅饼”
},
系列:[
{
数据:[{y:100,姓名:“女性”},{y:50,姓名:“男性”}]
}
]
};
类应用程序扩展了React.Component{
构造函数(){
超级();
此.state={
图表选项:空
};
this.setState({chart_options:options},()=>{
log(“this.state-”,this.state);
log(“选项-”,选项);
});
}
onFilterClickHandler=()=>{
log(“hi”,this.state.chart\u选项);
};
render(){
常数键=1;
返回(
海图
);
}
}
render(,document.getElementById(“根”));
您正在构造函数内部调用setState
(当组件尚未装入时)
要获取预期的console.log
输出,请从lifecycle方法调用setState
:
类应用程序扩展了React.Component{
构造函数(){
超级();
此.state={
图表选项:空
};
}
componentDidMount(){
this.setState({chart_options:options},()=>{
log(“this.state-”,this.state);
log(“选项-”,选项);
});
console.log(this.state);
}
onFilterClickHandler=()=>{
log(“hi”,this.state.chart\u选项);
};
render(){
常数键=1;
返回(
海图
);
}
}
检查答案,你就会知道哪里出了问题。为什么在构造函数()中使用setState?这是坏习惯!如果要为初始this.state.chart_选项设置值“options”,则应在声明this.state.chart_options=options时设置其方向。
class App extends React.Component {
constructor() {
super();
this.state = {
chart_options: null
};
}
componentDidMount() {
this.setState({ chart_options: options }, () => {
console.log("this.state - ", this.state);
console.log("options - ", options);
});
console.log(this.state);
}
onFilterClickHandler = () => {
console.log("hi", this.state.chart_options);
};
render() {
const key = 1;
return (
<div>
<div>
<label>
<input
type="checkbox"
value={key}
onClick={this.onFilterClickHandler}
/>
</label>
</div>
<h2>Highcharts</h2>
<PieChart highcharts={Highcharts} options={options} />
</div>
);
}
}