cors-proxy-server – npm

I wanted to try out some Angular code against a demo odata service, but when requesting data from another domain in a web browser (the angular context) you might get:

Access to XMLHttpRequest at ‘http://services.odata.org/V4/OData/OData.svc/Products?$format=json’ from origin ‘http://localhost:4200’ has been blocked by CORS policy: Response to preflight request doesn’t pass access control check: Redirect is not allowed for a preflight request.

To get around this problem you could use a node proxy like this one:

Source: cors-proxy-server – npm

Install and start it up. Now we can call the odata service by prepending the proxy url before the actual api endpoint like this:
http://localhost:9090/http://services.odata.org/V4/OData/OData.svc/Products

Notice the double http://

The entire CORS problem can be summarized like this:

The web browser will prevent javascript to get a response from the service at domain x if that server does not explicitly say its ok to respond the remote caller. In our case our source domain is ‘localhost’ and the services.odata.org haven’t added that as a valid domain to respond to according to the web browser.

More info regarding CORS here: https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS

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