AngularJS Error: Cannot use 'in' operator to search for '$ctrl' in

Question

I have the directory component passing a function to the question component. The question component is to take an input, and then update the directory component with this input via the function. When the question component tries to access this function, there is the JS error: angular.min.js:123 TypeError: Cannot use 'in' operator to search for '$ctrl' in Lee. What am I doing incorrectly to trigger this error?

https://plnkr.co/edit/hXjhhJcCWPcavp8Z8BRa?p=preview

let directoryTemplate = 
  '<question on-click="$ctrl.updateLastName()"></question>' +
  '<br />' +
  'Full name: {{$ctrl.fullName}}';

class directoryController {
  constructor() {
    this.fullName;
    this.firstName = 'Jack';
  }
  updateLastName(lastName) {
    this.fullName = `${this.firstName} ${lastName}`;
  }
}


let questionTemplate = 
  '<input ng-model="$ctrl.input" />' +
  '<button ng-click="$ctrl.onClick($ctrl.input)">Submit</button>';

class questionController {
  constructor() {
    this.input;
  }
}


angular
  .module('app', [])
  .component('directory', {
    template: directoryTemplate,
    controller: directoryController
  })
  .component('question', {
    template: questionTemplate,
    controller: questionController,
    bindings: {
      onClick: '&'
    }
  });

Answer 1

A similar question has been answered here: AngularJS Directive element method binding - TypeError: Cannot use 'in' operator to search for 'functionName' in 1

In a nutshell, in your template calling the component, you need to pass the signature of your function (including the argument's name):

<question on-click="$ctrl.updateLastName(lastName)">

And in your component you need to call your function with a JSON containing the lastName:

<button ng-click="$ctrl.onClick({lastName: $ctrl.input})">

See the uploaded plunker: https://plnkr.co/edit/iOA29KGEbl6NLubP1cvb?p=preview

By the way you should use ES6 template strings for your multiline templates, like you did for updateLastName method (see https://developers.google.com/web/updates/2015/01/ES6-Template-Strings).