使用React和Express阻止跨域请求 [英] Cross-Origin Request Blocked with React and Express

问题描述

因此，当我尝试使用React将数据发送到后端时，我遇到了此错误。据我了解，我需要允许后端和 .htaccess 文件中的通信。这是我使用的一些链接：

So I hit this error, when I was trying to send data to the back end using React. From what I learnt I need to allow the communication on the back-end and in the .htaccess file. Here are some of the links I used:

没有访问控制允许来源-节点/ Apache端口问题

Access-Control-Allow-Origin标头如何工作？

他们两个都有代码，但这没有帮助。

Both of them have code, but it didn't help.

到目前为止，我的服务器端代码是这样的：

So far my Server-side code is this:

app.use(function (req, res, next) {
    // Website you wish to allow to connect
    // res.setHeader('Access-Control-Allow-Origin', 'http://localhost:3000');

    res.setHeader('Access-Control-Allow-Origin', '*');

    // Request methods you wish to allow
    res.setHeader('Access-Control-Allow-Methods', 'POST');

    // Request headers you wish to allow
    res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');

    // Set to true if you need the website to include cookies in the requests sent
    // to the API (e.g. in case you use sessions)
    res.setHeader('Access-Control-Allow-Credentials', true);

    // Pass to next layer of middleware
    next();
});

这是我的客户端代码：

sendMail(e) {
    e.preventDefault();
    var name = document.getElementById('name').value;
    var contactReason = document.getElementById('contactReason').value;
    var email = document.getElementById('email').value;
    var additionalInfo = document.getElementById('additionalInfo').value;
    var body = {
        name: name,
        contactReason: contactReason,
        email: email,
        additionalInfo: additionalInfo,
    };
    console.log(JSON.stringify(body));
    fetch('http://localhost:4000/', {
        method: 'POST',
        body: body,
    }).then(r => console.log(r)).catch(e => console.log(e));
}

那么我想念什么？我没有 .htaccess 文件，但是我在本地完成所有操作，因此不确定是否可以使用它。

So what am I missing? I do not have an .htaccess file, but I'm doing it all locally so I'm not sure if I can even use it.

在我看来，我同意了我所需要的一切，但我想这还不够。

It looks to me like I'm allowing all I need, but I guess it's not enough.

如果您要标记作为重复项，请至少确保答案涵盖了我的问题。

If you're going to mark as a duplicate, please at least make sure my issues are covered by the answer.

推荐答案

有一个名为cors的节点包，它使

There's a node package called cors which makes it very easy.

$ npm install cors

const cors = require('cors')

app.use(cors())

您不需要任何配置即可允许全部操作。

You don't need any config to allow all.

有关更多信息，请参见Github存储库： https://github.com/expressjs/cors

See the Github repo for more info: https://github.com/expressjs/cors

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