有人可以解释这个javascript（可能是angularJS）语法的含义吗？

Question

Currently learning AngularJS. This was given as an example:

app.config(function ($routeProvider) { 
  $routeProvider 
    .when('/', { 
      controller: 'HomeController', 
      templateUrl: 'views/home.html' 
    }) 
    .otherwise({ 
      redirectTo: '/' 
    }); 
});

I don't understand this syntax of beginning the line with a property (ie .when or .otherwise . What object are these properties linked to? I'm assuming its $routeProvider , but two properties are being called it seems, and ive never seen properties accessed on a different line than the object. what does the entire structure of code mean? It's completely foreign to me. Is this an angularJS thing or did I learn javascript way too fast?

Answer 1

它会调用$routeProvider上的when方法， $routeProvider不是调用when调用结果的otherwise方法（ when将返回$routeProvider - 它被称为Fluent Interface ）。

Answer 2

It's basic JavaScript syntax. The .when() and .otherwise() are just function calls via property references. The fact that there are two of them just means that .when() returns an object, and probably the $routeProvider object itself. Thus, the return value from .when() can be used to invoke another method on the same object.