如何解决在ReactJS中以“未处理的拒绝TypeError:that.setState不是函数”的方式获取错误
我目前正在研究一个动态图表,该图表会根据Slider值进行更改。我搜索了一个解决方案,每个人都说我需要绑定它才能使此错误消失。但是我仍然尝试以所有可能的方式绑定该函数,但仍然出现此错误:
未处理的拒绝(TypeError):that.setState不是函数。
相关代码:
class Home extends React.Component {
constructor(props) {
super(props);
this.state = {
value: 0,slideValue: 200,slidebgColor: "47CF8E",type: 'bar',data: {
labels: [0],datasets: [{
label: '',data: [0,1],backgroundColor: [
'rgba(255,99,132,0.2)'
]
}]
},options: {
legend: {
display: false
},scales: {
yAxes: [{
display: false,ticks: {
beginAtZero: true,autoskip: true
}
}],xAxes: [{
display: false
}]
}
}
}
this.handleSliderEvent = this.handleSliderEvent.bind(this);
}
componentDidMount() {
console.log("inside componentDidMount");
}
getChartData = e => {
const data1 = this.state.data;
const slideValue = this.state.slideValue;
const backColor = ["pink","purple","blue","green","lightblue","neon","red","lightgreen","yellow","grey","lightgrey","orange"]
for (let i = 0; i < slideValue; i++) {
const randomNumber = Math.ceil(Math.random() * slideValue);
data1.labels[i] = randomNumber;
data1.datasets[0].data[i] = randomNumber;
data1.datasets[0].backgroundColor[i] = "purple";
}
this.setState = {
data: data1
}
return data1;
}
handleSliderEvent = async (event) => {
let slideValue1 = event;
let that = this;
that.setState({
slideValue: slideValue1
})
};
render() {
const type = this.state.type;
const options = this.state.options;
const data = this.state.data;
const slideValue = this.state.slideValue;
const value = this.state.value;
return (
<div style={{ display: "inline-flex" }}>
<div style={{ height: 400,display: "inline-flex",paddingLeft: "20px" }}>
<Slider
defaultValue={200}
vertical
progress
min={0}
max={this.state.slideValue}
onChange={this.handleSliderEvent}
/>
</div>
<div style={{ display: "inline-flex",position: "relative",width: 600,height: 550,paddingLeft: "10%" }}>
<Bar
type={type}
options={options}
data={this.getChartData}
/>
</div>
</div>
);
}
}
export default Home;
任何人都可以建议出什么问题了吗?
解决方法
您正在呼叫:
that.setState(...);
而不是:
this.setState(...);
您的代码应如下所示:
handleSliderEvent = async (event) => {
let slideValue1 = event;
// let that=this;
console.log("slideValue :",slideValue1)
//that.setState ({
this.setState({
slideValue: slideValue1
});
console.log(this.state.slideValue);
};
,
是否有使用let that = this
的理由?
做类似的事情更好吗?
handleSliderEvent = async (event) => {
this.setState({
slideValue: event
})
};
除了我相信您的TypeError来自其他地方:
getChartData=e=>{
...
this.setState = { data: data1 }
代替使用:
this.setState({ data: data1 })
,
问题在于getChartData
中的这段代码:
this.setState = {
data: data1
}
您要重新分配setState
函数,而不用更新的数据调用它。这意味着下次您尝试调用this.setState
时,它将中断,因为现在它是一个对象而不是函数。只需将其更改为此:
this.setState({
data: data1
})
此外,如注释中所述:let that = this
以及构造器中的绑定都是无用的。箭头功能不需要该替代方法。
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