Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://localhost:9001/api/size/get. (Reason: CORS header 'Access-Control-Allow-Origin' missing).

打开API项目录，命名用NuGet安装Microsoft.AspNet.WebApi.Cors:

在WebApiConfig.cs中，添加下面代码：

 private static void EnableCrossSiteRequests(HttpConfiguration config)

        {

            var cors = new EnableCorsAttribute(

              origins: "*",

              headers: "*",

              methods: "*"

              );

            config.EnableCors(cors);

        }

在路由中启用CROSS，说对整个API项目有效...