解决这个问题很简单，只需要几个步骤，不用担心任何事情。

请遵循以下步骤来解决它。

open (https://www.npmjs.com/package/cors#enabling-cors-pre-flight) go to installation and copy the command npm install cors to install via Node.js in a terminal go to Simple Usage (Enable All CORS Requests) by scrolling. Then copy and paste the complete declaration in your project and run it...that will work for sure... copy the comment code and paste in your app.js or any other project and give a try...this will work. This will unlock every cross origin resource sharing...so we can switch between servers for your use

JavaScript XMLHttpRequest和Fetch遵循同源策略。所以, 使用XMLHttpRequest或Fetch的web应用程序只能生成HTTP 请求到自己的域。

来源:https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS

你必须从你的服务器端发送Access-Control-Allow-Origin: * HTTP报头。

如果你使用Apache作为你的HTTP服务器，那么你可以像这样把它添加到你的Apache配置文件中:

<IfModule mod_headers.c>
    Header set Access-Control-Allow-Origin "*"
</IfModule>

Mod_headers在Apache中默认是启用的，但是，你可能想通过运行以下命令来确保它是启用的:

 a2enmod headers

在PHP中，你可以添加头文件:

<?php
    header("Access-Control-Allow-Origin: *");
    header("Access-Control-Expose-Headers: Content-Length, X-JSON");
    header("Access-Control-Allow-Methods: GET, POST, PATCH, PUT, DELETE, OPTIONS");
    header("Access-Control-Allow-Headers: *");
    ...

对于那些使用带有API网关的Lambda集成代理的人，您需要配置您的Lambda函数，就像您直接向它提交请求一样，这意味着函数应该正确地设置响应头。(如果你使用自定义lambda函数，这将由API网关处理。)

// In your lambda's index.handler():
exports.handler = (event, context, callback) => {
    // On success:
    callback(null, {
        statusCode: 200,
        headers: {
            "Access-Control-Allow-Origin" : "*"
        }
    }
}

在我的Apache VirtualHost配置文件中，我添加了以下几行:

Header always set Access-Control-Allow-Origin "*"
Header always set Access-Control-Allow-Methods "POST, GET, OPTIONS, DELETE, PUT"
Header always set Access-Control-Max-Age "1000"
Header always set Access-Control-Allow-Headers "x-requested-with, Content-Type, origin, authorization, accept, client-security-token"

RewriteEngine On
RewriteCond %{REQUEST_METHOD} OPTIONS
RewriteRule ^(.*)$ $1 [R=200,L]

我们的团队在使用Vue.js、Axios和c# Web API时偶尔会遇到这种情况。在您试图命中的端点上添加路由属性为我们修复了它。

[Route("ControllerName/Endpoint")]
[HttpOptions, HttpPost]
public IHttpActionResult Endpoint() { }