Angular Js 中控制器的文档查询选择器

Document query selector for a controller in Angular Js

我有一个这样命名的控制器:

<div ng-controller="MainController as main" class="containerWrap">

我试过这个来选择我的控制器以进一步发挥作用:-

var a = document.querySelector('[ng-controller=MainController as main]');
var b = angular.element(chatElement).scope();

它给出一个错误:-

Uncaught SyntaxError: Failed to execute 'querySelector' on 'Document': '[ng-controller=MainController as main]' is not a valid selector.

我也只尝试了 MainController :-

这给出了:-

a=null
b=undefined

有人能帮忙吗?

var a = document.querySelector('[ng-controller="MainController as main"]');