Cross-domain network resource file download

Question

Under normal circumstances, it is impossible to send cross-domain requests to download files.Take downloading Yuque as an example: you can see that if you directly access the download address, a cross-domain error will be reported

Resolve

At this time, we can forward the request through the nginx configuration proxy to complete the download:

location ^~ /yuque/ {proxy_pass https://app.nlark.com/yuque-desktop/;}

Copy

Description: When we send a request like /yuque/ locally, nginx will forward the request (Note: / must be added at the end, otherwise it is a proxy request, addThen the forwarding request), will forward /yuque/ to the following https://app.nlark.com/yuque-desktop/

Then we rewrite the download request:

var xhr = new XMLHttpRequest();xhr.open("GET", "/yuque/1.1.4/Yuque-1.1.4.exe", true);xhr.send();

Copy

This time, we will not directly access the Yuque download address, but visit our local address, and then nginx will forward our request and forward /yuque/ to https://app.nlark.com/yuque-desktop/, then the forwarded request becomes https://app.nlark.com/yuque-desktop/1.1.4/Yuque-1.1.4.exe.Since we do not directly request the download address, but the local address of the request, and forward the request through the proxy of nginx, there is naturally no cross-domain problem (if you don't understand, you can read the article I wrote about nginx reverse proxy before)

Afterword

Because nginx does not pass reverse proxy but forward proxy requests, in this process, the resource passes through the nginx server once, and then nginx sends the resource to the requester, so this process needs to consume the location of nginxserver traffic.