What does the number of network request interface layers (2/3 layers) mean

For example, I now get a network interface data  

  Then generally, you only need to see Part of yellow area

Then take it to the code to search , You find it written like this , Only two interfaces are needed here

At this time, the interface given to me by the back end , This is the third floor

This means three layers and two layers , If there is only two-tier interface , Just write workers/list Just fine

Then I just kept prompting the path error , We consulted our predecessors , He said it was because the backstage forgot to add app This word , Because this involves a permission problem , Small programs only add app To get .

Sure enough, it was added in the background app after , I can visit here normally

util It's a tool util.request It's a tool , And this way of writing is already get Request the  

Then check whether I get this interface