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

问题

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 => {
    //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 => {
    //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!

回答1:

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.

回答2:

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

回答3:

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

回答4:

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.

回答5:

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.

回答6:

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 :)

回答7:

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;
    }
}

来源：https://stackoverflow.com/questions/41497674/access-control-allow-origin-issue-when-api-call-made-from-react-isomorphic-ap

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javascript

node.js

reactjs

isomorphic-javascript

axios