Meaning of < and > in JavaScript export or function definitions

Question

In javascript codes, I see statements like this:

export default mongoose.model<UserInterface & mongoose.Document>('User', UserSchema)

this example is taken from repo: https://github.com/santiq/nodejs-auth.git

It would be great if someone could explain what <UserInterface & mongoose.Document> means? You can find similar statements, ie Promise<any> few times in the same repo. It is not the first time I see this kind of statement and I cannot find any explanation of it. Since I am learning JavaScript very actively it is important for me to understand advanced syntax and any "ninja" codes.

Thanks in advance Jo

Answer 1

That's not JavaScript, that's TypeScript.

• The < and > delimit type-parameter arguments.
• The & denotes an Intersection Type .

In this case, it's declaring that the module's default exported item is a model object that concerns any object that has members belonging to both UserInterface and Document simultaneously.

Answer 2

That is great help guys. Great thanks. I didn't expected that answer. I went through internet back and forth with no answer for my question simply because I did not consider that it could be anything else than JS.

Thanks a million Jo