What is cross-domain and cross-domain request scheme
A domain is such a concept: We believe that if the protocol + domain + port number are the same, then that is the same domain.
For safety reasons, in order to avoid CSRF attack, the browser will intercept the Ajax request non-homologous.
Solution:
1 jsonp
Advantages: limited by the same origin policy; it's better compatibility, can run more ancient browser.
Cons: only supports GET requests without the support of other types of HTTP POST requests, request
2 hearts
Pros: Supports all types of HTTP requests; can be initiated using normal XMLHttpRequest request and obtain data than JSONP have better error handling.
Cons: Although most modern browsers already support CORS, CORS compatibility but not as JSONP, some older browsers only support JSONP