Javascript cross-origin method aggregation _ javascript skills

This article mainly summarizes information about how javascript implements cross-origin. For more information, see the restrictions on the same-origin policy, XMLHttpRequest only allows requests to resources of the current source (including domain names, protocols, and ports.

Differences between json and jsonp:

JSON is a data exchange format, while JSONP is an unofficial cross-domain data exchange protocol created by developers.

Script tags are often used to load resources in different domains and bypass the same-origin policy. (All files with the src attribute can be obtained from other countries ).
If the remote data requested is a piece of executable js, the js will be executed (equivalent to eval ).

Method 1:

Request by using the script tag (