I want to validate only numbers are key-in in the input field for **IC NUMBER** text field. How should I parse the input entered by the user into int?

> 
> 
> ```
> <form>
>     <ion-list>
> 
>       <ion-item>
>         <ion-input type="text"  placeholder="USERNAME" ></ion-input>
>       </ion-item>
> 
>       <ion-item>
>         <ion-input type="password"  placeholder="PASSWORD"></ion-input>
>       </ion-item>
> 
>       <ion-item>
>         <ion-input type="text"  placeholder="IC NUMBER"></ion-input>
>       </ion-item>
> 
>              <div padding>
>            <button ion-button   color="dark" block>SUBMIT</button>
>         </div>
>      </ion-list>
> </form>
> 
> ```
> 
>