Reactjs 字符串值未传递到displayName

一些语法错误需要修复。当我将this.signupEmail.value传递给displayName时，它将变为null。以下是信息：

• 其他一切都很好。在此之前，this.signupEmail.value已被使用，但没有任何问题要执行auth.createUser
• 对于测试，如果我像这样直接将文本字符串传递给displayName

它会很好地工作

有什么建议吗？谢谢

handleRegister(event) { 
        this.toggleModalSignUp();        
        auth.createUserWithEmailAndPassword(this.signupEmail.value,this.signupPassword.value)
        .then(() => { 
            var user = auth.currentUser;            
            if (user != null) {                
                user.sendEmailVerification()                
                alert('Account verification sent to your mailbox. Please check your email and verify!') 
                
                user.updateProfile({ displayName: this.signupEmail.value })                
            }         
        })
        .catch(error => {console.log(error); alert(error)})        
        event.preventDefault();
    }    

handleRegister(event) { 
        this.toggleModalSignUp();        
        auth.createUserWithEmailAndPassword(this.signupEmail.value,this.signupPassword.value)
        .then(() => { 
            var user = auth.currentUser;            
            if (user != null) {                
                user.sendEmailVerification()                
                alert('Account verification sent to your mailbox. Please check your email and verify!') 
                
                user.updateProfile({ displayName: this.signupEmail.value })                
            }         
        })
        .catch(error => {console.log(error); alert(error)})        
        event.preventDefault();
    }