import?React?from?'react'

class?CommentBox?extends?React.Component{

????constructor(props){

????????super(props)

????????this.state={

????????????value:''

????????}

????????this.handleChange=this.handleChange.bind(this)

????????this.handleSubmit=this.handleSubmit.bind(this)

????}

????handleChange(event){

???????this.setState({

???????????value:?event.target.value

???????})

????}

????handleSubmit(event){

????????this.setState({

????????????alert(this.state.value)

????????????event.preventDefault()

????????})

????}

????render(){

????????return(

????????????<form?className="p-5"?onSubmit={this.handleSubmit}>

????????????????<div?className="form-group">

????????????????????<label>留言內容</label>

????????????????????<input?type="text"??className="form-control"?placeholder="請輸入內容"?value={this.state.value}?onChange={this.handleChange}/>

????????????????</div>

????????????????<button?type="submit"?className="btn?btn-primary">留言</button>

????????????</form>

????????)

????}

}

export?default?CommentBox

報錯：

Failed to compile

./src/components/CommentBox.js
 ?Line 18: ?Parsing error: Unexpected keyword 'this'

 ?16 | ?? ?handleSubmit(event){
 ?17 | ?? ? ? ?this.setState({
> 18 | ?? ? ? ? ? ?alert(this.state.value)
 ?? ?| ?? ? ? ? ? ? ? ? ?^
 ?19 | ?? ? ? ? ? ?event.preventDefault()
 ?20 | ?? ? ? ?})
 ?21 | ?? ?}