我正在将Gatsby和Express与Fetch一起使用。托管在Heroku上。

调用注册端点时，出现以下错误：

“从来源“示例/客户端”获取“示例/ api”处的访问已被CORS策略阻止：请求的资源上不存在“ access-control-allow-origin”标头。如果响应不透明，您可以根据需要，将请求的模式设置为“ no-cors”，以在禁用CORS的情况下获取资源。”

在对我的注册终结点进行此调用之前，我正在向Get终结点发送成功的调用，该Get终结点发送了csurf令牌。

这是我的服务器代码：

APP配置

app.use(
  cors({
     origin: "front-end-url",methods: "GET,HEAD,PUT,PATCH,POST,DELETE",allowedHeaders: [
    "Content-Type","access-Control-Allow-Headers","access-control-allow-origin","Authorization","csrf-token"
  ],exposedHeaders: [
    "Content-Type",maxAge: 3600,preflightContinue: true,credentials: true
  })
);
...

//configure pre-flight options 

app.options("/getToken",cors());
app.options("/checkAuth",cors());
app.options("/signIn",cors());
app.options("/signUp",cors());

API端点

=>获取csurf令牌

 app.get("/getToken",(req,res) => {
    res.cookie("XSRF-TOKEN",req.csrfToken());
    res.end();
  });

=>注册路线（失败，并显示错误）

  app.post(
    "/signUp",res,next) => {
      database operations...
    },passport.authenticate("login"),next) => {
      res.send({ user: req.user,authStatus: true });
    }
  );

前端代码

  userSignUp = async (email,password,resetform) => {
    console.log("THis is a test of the emergency..")
    await fetch(process.env.API + "getToken",{
      mode: "cors",// no-cors,cors,*include
      cache: "no-cache",// *default,no-cache,reload,force-cache,only-if-cached
      credentials: "include",// include,*include,omit
      headers: {
        "content-type": "application/json",},method: "GET",})
    const token = Cookies.get("XSRF-TOKEN")
    const data = await fetch(process.env.API + "signUp",{
      body: JSON.stringify({ email: email,password: password }),mode: "cors","csrf-token": token,method: "POST",}).catch(error => this.setState({ isError: true }))
    if (data.ok) {
      console.log(data.ok)
      data.json().then(content => {
        console.log(content)
        this.props.changeAuth(content.authStatus)
        this.props.setCategories(content.user.categories)
        this.props.getEvents(content.user.events)
        resetform()
      })
    } else {
      this.setState({
        isError: true,})
    }
  }