javascript - About cross-domain login

Question

There are two websites, a.com and b.com. After logging into the website a.com, you will automatically log in to b.com, and vice versa. In short, the login and logout status of the two websites remain synchronized.
In addition, in addition to a.com and b.com, there are countless websites with the same different domain names that need to synchronize their login status.

我想大声告诉你 · Answer

SSO(single sign on)

The situation you mentioned can be solved by the above solution. There are many ways to implement this solution. You can check it out.

I will also give you a simple example:

When you log in to a website,

1) He obtained your username and password and sent them to the background

2) After passing the verification, an encrypted authentication character oauth will be generated by the backend

3) Then send a message to the front desk saying that you have successfully logged in, and then use the background script to insert relevant authentication information into a series of specified domain names.

In this way, although you are only logged in under one domain name, your authentication information will also be available under other domain names. Of course, the above is just one implementation plan, there are others

The implementation method is quite different from this.

淡淡烟草味 · Answer

All browser state saving methods are saved by domain. Taking cookies as an example, assume you want to be in the a.com使用b.com的授权登录，当你登录的时候调用了oauth，那么其实你是跳转到b.com进行登录的，那么你的浏览器就会保存b.com登录状态。那么当你在c.com登录的时候，你的浏览器已经保存了b.com的登录状态，那么自然就可以自动登录了。当然，a.com和c.com在浏览器中是无法获取到b.com state.