The so-called same-origin policy, referring to the limit browser access to the different ways the source of the script or text carried out. Js source of such a set can not be read or introducing a source of element attributes b. So first define what is the origin, the so-called homologous refers to two pages have the same protocol, host (also often said domain name), port, three elements are indispensable.
Look at the following comparison becomes clear:
| Uhrilal | URL2 | Explanation | Whether to allow communication |
| https://github.com/LoveCatDog/StudyOne | https://github.com/LoveCatDog/cms-admin-mall | Protocol, the domain name, the same port | allow |
| https://github.com/LoveCatDog/cms-admin-mall | https://github.com:8080/LoveCatDog/cms-admin-mall | Agreement, the same domain name, different ports | Not allowed |
| http://github.com/LoveCatDog/cms-admin-mall | https://github.com/LoveCatDog/cms-admin-mall | The same name, the same port, different protocols | Not allowed |
| https://github.com/LoveCatDog/cms-admin-mall | https://cnblogs.com/LoveCatDog/cms-admin-mall |
Protocol, same port, different domain name | Not allowed |
| https://github.com/LoveCatDog/cms-admin-mall | https://www.github.com/LoveCatDog/cms-admin-mall | Protocol, the same port, the same primary domain, different subdomains | Not allowed |
Interaction between the different sources of the same origin policy restrictions aimed primarily js the XMLHttpRequest and other requests, write code, you also often references js file to other domain names, style files, image files or something, you do not receive these limit