Access-Control-Allow-Origin issue when API call made from React Isomorphic app

Question

I m running into an issue with my isomorphic JavaScript app using React and Express     I am trying to make an HTTP request with axios get when my component mounts  componentDidMount       const url    http   ufc-data-api ufc com api v3 iphone fighters title holders     axios get url  then  res   gt          use res to update current state          I am getting a status 200 res from the API  but I am not getting any response data and getting an error in my console  XMLHttpRequest cannot load http   ufc-data-api ufc com api v3 iphone fighters title holders   No  Access-Control-Allow-Origin  header is present on the requested resource   Origin  http   localhost 3000  is therefore not allowed access    However  if I make the request in my server js  const url    http   ufc-data-api ufc com api v3 iphone fighters title holders   axios get url  then res   gt          console log res         It works fine and I get response data when the server starts  Is this an issue with the actual API or am I doing something wrong  If this was a CORS issue I m guessing the request in server js wouldn t work either  Thanks

User · Answer

Because the server don t have CORS header  so you are not allowed to get the response   This is header from API that I captured from Chrome brower   Age 28 Cache-Control max-age 3600  public Connection keep-alive Date Fri  06 Jan 2017 02 05 33 GMT ETag  18303ae5d3714f8f1fbcb2c8e6499190  Server Cowboy Status 200 OK Via 1 1 vegur  1 1 e01a35c1b8f382e5c0a399f1741255fd cloudfront net  CloudFront  X-Amz-Cf-Id GH6w6y P5ht7AqAD3SnlK39EJ0PpnignqSI3o5Fsbi9PKHEFNMA0yw   X-Cache Hit from cloudfront X-Content-Type-Options nosniff X-Frame-Options SAMEORIGIN X-Request-Id b971e55f-b43d-43ce-8d4f-aa9d39830629 X-Runtime 0 014042 X-Ua-Compatible chrome 1 X-Xss-Protection 1  mode block   No CORS header in response headers

User · Answer

I don t know if this will help but I was getting the same error when remote debugging a react-native application  I was running the debugger on 192 168 x x 8081  I read a little bit on this Cross-Origin Resource Sharing  CORS  to educate myself on what CORS is   I m a beginner  and changed my URL from IP 8081 to localhost 8081 and my issue was resolved

User · Answer

Use the google Chrome Extension called Allow-Control-Allow-Origin     It modifies the CORS headers on the fly in your application

User · Answer

You can use this code when using vs code on debugging mode       runtimeArgs     --disable-web-security   --user-data-dir   ChromeUserData      launch json       version    0 2 0      configurations                  type    chrome          request    launch          name    Chrome disable-web-security          url    http   localhost 3000          webRoot      workspaceFolder           runtimeArgs              --disable-web-security            --user-data-dir   ChromeUserData                         Or directly run   Chrome --disable-web-security --user-data-dir   ChromeUserData

User · Answer

I had the same problem  the other answers are correct but there is another solution  you can set response header to allow cross-origin access  according to this post you have to add the following codes before any app get call   app use function req  res  next      res header  Access-Control-Allow-Origin           res header  Access-Control-Allow-Headers    X-Requested-With      next            this worked for me

User · Answer

Fix Without Using External Proxy or Chrome Extension CORS should be enable in server side  if you can not activate it on server  for example using external API  create a middleware React - gt  Middleware - gt  Orginal Server   Create a Node js project  Middleware  and use below code in app js  const express   require  quot express quot    var cors   require  cors   const app   express    app use cors     const   createProxyMiddleware     require  http-proxy-middleware    app use   api   createProxyMiddleware        target   http   localhost 8080      original url     changeOrigin  true         secure  false      onProxyRes  function  proxyRes  req  res           proxyRes headers  Access-Control-Allow-Origin                     app listen 5000      This will pass the request http   localhost 5000 api xxx to  original server  for example http   localhost 8080 api xxx   and returns the result to client   Change client  React  to call proxy and get data without CORS error  axios get  http   localhost 5000 api xxx     proxy uri      headers          authorization    xxxxxxxxxx           Content-Type    application json           then function  response       console log response         run node project node app js and react project npm start

User · Answer

CORS is a browser feature  Servers need to opt into CORS to allow browsers to bypass same-origin policy  Your server would not have that same restriction and be able to make requests to any server with a public API  https   developer mozilla org en-US docs Web HTTP Access control CORS  Create an endpoint on your server with CORS enabled that can act as a proxy for your web app

User · Answer

I faced the same error today  using React with Typescript and a back-end using Java Spring boot  if you have a hand on your back-end  you can simply add a configuration file for the CORS   For the below example I set allowed origin to   to allow all but you can be more specific and only set url like http   localhost 3000   import org springframework boot web servlet FilterRegistrationBean  import org springframework context annotation Bean  import org springframework context annotation Configuration  import org springframework web cors CorsConfiguration  import org springframework web cors UrlBasedCorsConfigurationSource  import org springframework web filter CorsFilter    Configuration public class AppCorsConfiguration        Bean     public FilterRegistrationBean corsFilter             UrlBasedCorsConfigurationSource source   new UrlBasedCorsConfigurationSource            CorsConfiguration config   new CorsConfiguration            config setAllowCredentials true           config addAllowedOrigin               config addAllowedHeader               config addAllowedMethod               source registerCorsConfiguration        config           FilterRegistrationBean bean   new FilterRegistrationBean new CorsFilter source            bean setOrder 0           return bean

User · Answer

I think the answer for your question is here  To have Chrome send Access-Control-Allow-Origin in the header  just alias your localhost in your  etc hosts file to some other domain  like  127 0 0 1   localhost yourdomain com

User · Answer

install cors using terminal command             npm install cors            If your using express in your node server just add         var cors   require  cors            app use cors               and re-run the server  your problem is rectified  1   1           If you won t be understood then see below image     https   i stack imgur com Qeqmc png

User · Answer

Create-React-App has a simple way to deal with this problem  add a proxy field to the package json file as shown below  quot proxy quot    quot http   localhost 8081 quot

User · Answer

I was having the same problem with the fetch command  A quick look at the docs from here tells us this      If the server you are requesting from doesn t support CORS  you should get an error in the console indicating that the cross-origin request is blocked due to the CORS Access-Control-Allow-Origin header being missing    You can use no-cors mode to request opaque resources   fetch  https   bar com data json       mode   no-cors      cors  by default     then function response         Do something with response

[javascript] 'Access-Control-Allow-Origin' issue when API call made from React (Isomorphic app)

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