It is not clear what exactly angular’s $templatecache is used for.

  node.js, question

After reading many articles on performance optimization (about angular), almost all mentioned $templatecache. I don’t know what this thing does, do you have a great god to explain it or recommend relevant articles to me

The template is cached during the application startup phase. Let’s give a simple example:

$templateCache.put("page.html","<div>i am page to be load</div>");

When a service needs to call template, such as the modal box, it does not need to go to http to fetch, and the cache inside is available.
You can pay attention to the debug network. Every time you call the modal box, you will initiate a request to get this template. Once cache, repeat request will not waste resources and the experience will be improved, because it is fast.