javascript - How do you solve cross-domain problems when separating front-end and back-end?

Currently when I am working on my blog, I consider using front-end and back-end separation, placing the front-end and back-end logic in two separate repositories and deploying them on two servers.

My main domain name is: godtail.cn (currently using ghost, new blog is being written...)

• The front-end domain name is: www.godtail.cn | godtail.cn | m.godtail.cn

• The backend domain name is: api.godtail.cn

But when communicating, I found that it prompted Cross-domain. Well, I thought it would not cross-domain when the main domain name was the same (the same domain name and different ports would also cross-domain).

Currently, there are two solutions that I know of:

1. Use JSONP. To be honest, I don’t particularly like using JSONP. I feel that it will cause security problems or reduce efficiency (these two points are just my guesses).
   Reason for guessing:

   • It can be accessed from any source. Is there any js injection?

   • Both the backend and the frontend need JSONP for processing. (It’s not pleasant to write, and all requests must use JSONP).

2. Add cross-domain header in backend

   • If there are many front-end domain names, many domain names need to be added and maintained. If other systems need to request your interface, add a cross-domain header? Not easy to deal with...

Does anyone have a better solution?

================【9-22 17:25】======================

In addition, if you set the cross-domain header, you can set the IP, which is only for internal calls. If external calls are required, it will not be satisfied. In addition, I am not sure if there are any compatibility issues with older versions of browsers.

Reply content:

Currently when I am working on my blog, I consider using front-end and back-end separation, placing the front-end and back-end logic in two separate repositories and deploying them on two servers.

My main domain name is: godtail.cn (currently using ghost, new blog is being written...)

• The front-end domain name is: www.godtail.cn | godtail.cn | m.godtail.cn

• The backend domain name is: api.godtail.cn

But when communicating, I found that it prompted Cross-domain. Well, I thought it would not cross-domain when the main domain name was the same (the same domain name and different ports would also cross-domain).

Currently, there are two solutions that I know of:

1. Use JSONP. To be honest, I don’t particularly like using JSONP. I feel that it will cause security problems or reduce efficiency (these two points are just my guesses).
   Reason for guessing:

   • It can be accessed from any source. Is there any js injection?

   • Both the backend and the frontend need JSONP for processing. (It’s not pleasant to write, and all requests must use JSONP).

2. Add cross-domain header in backend

   • If there are many front-end domain names, many domain names need to be added and maintained. If other systems need to request your interface, add a cross-domain header? Not easy to deal with...

Does anyone have a better solution?

================【9-22 17:25】======================

In addition, if you set the cross-domain header, you can set the IP, which is only for internal calls. If external calls are required, it will not be satisfied. In addition, I am not sure if there are any compatibility issues with older versions of browsers.

Of course, the backend adds Access-Control-Allow-Origin
As for the problem of too many front-end domain names you mentioned, let the backend use some tricks to handle it without any trouble
Thought: for Access-Control- Allow-Origin adds the target domain name (Origin request header) instead of a hard-coded domain name or *

Approximate implementation (pseudocode):

<code>// 允许跨域访问的域名数组
string[] allowOrigins = 
{
    "http://www.godtail.cn/", 
    "http://godtail.cn/", 
    "http://m.godtail.cn/",
};

// 判断 origin 是否是自己的前端域名，如果是则添加
if(allowOrigins.Count(x => x.Contains(Request.Headers["Origin"])) > 0)
    Response.Header.Add("Access-Control-Allow-Origin", Request.Headers["Origin"]);</code>

But then again, request headers can be simulated, so it is recommended to encrypt the interface request parameters and compress and obfuscate the front-end scripts
Refer to the interface encryption of NetEase Cloud Music (go grab the package and take a look)

Consider adding a cross-domain header to the backend to allow all domain names, and then filter the domain names in the code. Domain names that do not meet the requirements will directly return 404.

nginx reverse proxy... It turns out you asked and answered your own question...

Set the header 'Access-Control-Allow-Origin:*' on the server side;

This is what I mentioned above. You can specify the access address~

Forward domain name on a server that does not lose front-end code

Can’t the cross-domain header be written in regular form?

The first method I adopted, jsonp, callback, if there are too many such requests, it will be troublesome to write;
The second method, it didn’t work after I tried it, is to set Access-Control-Allow- on the response Origin..*?