how to make active previous all steps of selectedIndex step using angular material stepper and angular 6

Question

I have use angular material stepper and i need to activate all the previous steps till selectedIndex step in angular 6. I already tried by using linear stepper but i getting only active step for selectedIndex not for all previous index .Examble i have 5 steps and i select the 3rd one, I getting only 3 rd step in actively remaining 1st &2nd steps are inactive , I need to activate the 1st,2nd,3rd steps

angular 6 , angular material 6

in html

<div class="col-lg-7" *ngIf="!process">
                           <mat-horizontal-stepper [linear]="isLinear" 
 [selectedIndex]="currentStep" #stepper>
                             <ng-container *ngFor="let step of steps">
                                   <ng-template matStepperIcon="home">
                                       <mat-icon>home</mat-icon>
                                     </ng-template>
                               <mat-step  [editable]="isEditable">
                                 <ng-template matStepLabel>{{step}}</ng- 
    template>
                               </mat-step>
                             </ng-container>
                           </mat-horizontal-stepper>
                         </div>  

in ts

```
isLinear = true;
      process: Boolean;
      steps = [ "Ordered", "Packed", "Shipped", 'Transit', "Delivered" ];
      this.process = true;
        setTimeout(() => {
          this.currentStep = 2;
          this.process = false;
        }, 1500);

I expected first three steps are active mode but i got only 3rd step in active mode

Answer 1

You can mark the steps that are before the selected step as completed:

<mat-horizontal-stepper [linear]="isLinear" [selectedIndex]="currentStep" #stepper>
    <ng-container *ngFor="let step of steps; index as i">
        <ng-template matStepperIcon="home">
            <mat-icon>home</mat-icon>
        </ng-template>
        <mat-step #matStep [editable]="isEditable" 
                [completed]="matStep.interacted || i < currentStep">
            <ng-template matStepLabel>{{step}}</ng-template>
        </mat-step>
    </ng-container>
</mat-horizontal-stepper>