Preface: I am not trying to use reactive forms

What is the proper way to restrict white space in Angular2? I see [this](https://stackoverflow.com/questions/27322826/angular-restriction-to-not-allow-spaces-in-text-field) answer for AngularJS, but I am not sure if there is a better way to do this in Angular2. Say I have:

```
        <input
          placeholder="alert tag (25 max)"
          maxlength="25"
          value="alert"
          type="text"
          #alertTagInput
          [(ngModel)]="alertTag" >

```

The user can currently type in whitespace, how do I restrict that?