The method used to obtain the returned value of the target server on the homepage when the cross-origin request is submitted.

When the POST method is used, the form is submitted from Domain A to Domain B, and the result cannot be returned to the home page of Domain A using the jsonp method. Only the script reference method can be used. This GET request has many limitations.

When post is not used, you can do the following:

Before submission, the home page of Domain A dynamically generates an implicit IFRAME and prepares the page for receiving the returned values.

The action of form is the target page of Domain B, and the target is IFRAME.

The target page of B domain will return the value as the parameter and then redirect to the receiving page of a domain, but with JS or server side directly send jump code, construct http://a.com/receive? MSG = xxxx;

If the returned value is complex, you can even construct a form to automatically submit the form to Domain A and accept the page for a reverse call.

After the submission, IFRAME contains the page of Domain A and obtains the return value of the target page of Domain B from the parameter. Then, it can return the return value to the submitted homepage.