angular.js - Questions about custom filters in angularjs

Question

I was just looking at the angularjs todoMVC project and found that it customized a filter in the controller

$scope.$watch('TC.location.path()',function (path) {
            TC.Filters = {'/active':{completed: false},'/completed':{completed:true}}[path];
        });

Afterwards in view

<li ng-repeat="todo in TC.todos | filter:TC.Filters track by $index" ng-class="{completed: todo.completed, editing: todo === TC.editedTodo}">

My problem is mainly that I don’t understand the way the first piece of code is written

function (path) {
            TC.Filters = {'/active':{completed: false},'/completed':{completed:true}}[path];
        }

In this method, after passing in the path, different filters are selected based on the path.

I would like to ask if there is any documentation that introduces this method of selecting within a filter object.

Answer 1

Although the reason has been given upstairs, I guess you don’t quite understand it. Let me give you a document to see what $watch is. The document is here.

Answer 2

$scope.$watch('TC.location.path()',function (path) {
    TC.Filters = {'/active':{completed: false},'/completed':{completed:true}}[path];
});

The change of the path is monitored here. When the path changes, the parameters of the filter also change. In fact, it is the switching between completed and active data