Angular 4 & Material Stepper

Ok, it seems I found a solution (but it is not stated anywhere on the API).

1. Add a reference to the stepper, then add ViewChild with the reference in your component typescript file.
2. Create a method to change the index of the stepper.

HTML:

<mat-horizontal-stepper [linear]="true" #stepper>
    <!-- Content here -->
</mat-horizontal-stepper>

TS:

import { Component, ViewChild } from '@angular/core';
@Component({
    // ...
})
export class AppComponent {
    @ViewChild('stepper') stepper;

    /**
     * Changes the step to the index specified
     * @param {number} index The index of the step
     */
    changeStep(index: number) {
        this.stepper.selectedIndex = index;
    }
}

It is possible to jump to a specific stepper. MatStepper exposes a public property selectedIndex which specifies the currently selected step index. It can be set. The index starts at 0.

In your template:

Add an id to your stepper e.g. #stepper. Then add a button in your step, and pass the stepper id in a function on (click) like below:

<mat-horizontal-stepper [linear]="isLinear" #stepper>
    <!-- Your other steps here -->
    <mat-step [stepControl]="secondFormGroup">
        <!-- Content in the step -->
        <div>
            <!-- Other actions here -->                 
            <button mat-button (click)="resetStepper(stepper)">Reset</button>
        </div>
    </mat-step>
    <!-- More steps here -->
</mat-horizontal-stepper>

.. and in your typescript:

import { MatStepper } from '@angular/material';

exported YourOwnComponent {

  constructor() {}

  resetStepper(stepper: MatStepper){
     stepper.selectedIndex = 0;
  }
}

Stackblitz demo

In the html template , reference your stepper with #stepper

<mat-horizontal-stepper #stepper>
</mat-horizontal-stepper>

and in your typescript file declare the stepper

@ViewChild("stepper", { static: false }) stepper: MatStepper;

after that you can set the stepper step with his selectedIndex property

 this.stepper.selectedIndex = 0; //0 is the index of the first step