Enable/disable buttons with Angular

Set a property for the current lesson: currentLesson. It will hold, obviously, the 'number' of the choosen lesson. On each button click, set the currentLesson value to 'number'/ order of the button, i.e. for the first button, it will be '1', for the second '2' and so on. Each button now can be disabled with [disabled] attribute, if it the currentLesson is not the same as it's order.

HTML

  <button  (click)="currentLesson = '1'"
         [disabled]="currentLesson !== '1'" class="primair">
           Start lesson</button>
  <button (click)="currentLesson = '2'"
         [disabled]="currentLesson !== '2'" class="primair">
           Start lesson</button>
 .....//so on

Typescript

currentLesson:string;

  classes = [
{
  name: 'string',
  level: 'string',
  code: 'number',
  currentLesson: '1'
}]

constructor(){
  this.currentLesson=this.classes[0].currentLesson
}

DEMO

Putting everything in a loop:

HTML

<div *ngFor="let class of classes; let i = index">
   <button [disabled]="currentLesson !== i + 1" class="primair">
           Start lesson {{i +  1}}</button>
</div>

Typescript

currentLesson:string;

classes = [
{
  name: 'Lesson1',
  level: 1,
  code: 1,
},{
  name: 'Lesson2',
  level: 1,
  code: 2,
},
{
  name: 'Lesson3',
  level: 2,
  code: 3,
}]

DEMO

my.component.html:

<button [disabled]="isSubmitBtnDisabled" (click)="addGame()">Send</button>

my.component.ts:

export class My implements OnInit {
  isSubmitBtnDisabled: boolean= false;

   private someMethodYouCalled() {
      this.isSubmitBtnDisabled = true;   //Controls if button is disabled
   }
}