Make sure the browser actually supports CORS.Make sure you're testing via Scripts running via file:// have limited support for CORS.If you're trying to do a cross-domain XMLHttpRequest via CORS.You're using $.getJSON and included callback=? in the URL.You're using $.get and set dataType to jsonp.If you're trying to use JSONP, make sure one of the following is the case: Sounds like the recommended way to do it is to have your server read the Origin header from the client, compare that to the list of domains you would like to.To clarify for other people, here are the simple troubleshooting instructions:

That solved the second by no longer trying to perform a CORS request from a file:// URL. It does a little magic to change the request type from its default of 'json' to 'jsonp' if it sees the substring callback=? in the URL. The first was solved in a roundabout way by Darin's suggestion to use $.getJSON. However, file:// URLs produce a null Origin which can't be authorized via echo-back. One is to send Access-Control-Allow-Origin: * (which, if you were reaching Flickr via $.get, they must have been doing) while the other was to echo back the contents of the Origin header. There are two ways for CORS headers to signal that a cross-domain XHR is OK. I believe you mentioned you were running it from a file:// URL. That's where the Access-Control-Allow-Origin header came in. Make sure your request is Simple requests. If you want to access correctly, you can do so: Modify your server configuration and add the corresponding header to allow browser access. However, your browser supported CORS (Cross-Origin Resource Sharing) to allow cross-domain XMLHttpRequest if the server OKed it. The Access-Control-Allow-Origin is response header, CORS is meaningless if the client can control it. Weird CORS errors on fresh vue cli project. Vue Axios CORS policy: No Access-Control-Allow-Origin 4. You weren't passing a 'jsonp' type specifier to your $.get, so it was using an ordinary XMLHttpRequest. 2) Setup a development proxy in VueJs During development, you often see that the backend server is running on a different port than the frontend server. Adding Access-Control-Allow-Origin headers to vuejs CLI webpack server. For the record, as far as I can tell, you had two problems:

Vue axios access control allow origin