title: How to restrict input textbox to enter numbers only in Angular2 form?
body: <p>I have to restrict user to enter only numbers in a field in Angular2->form 
  I have solution but backspace is not working in input field 
  Can anybody have proper solution for that?</p>
  
  <p>form.html</p>
  
  <p><code>&lt;input (keypress)="keyPress($event)" minlength="8" maxlength="15" required /&gt;</code></p>
  
  <p>form.component.ts</p>
  
  <pre><code>keyPress(event: any) {
      const pattern = /[0-9\+\-\ ]/;
      let inputChar = String.fromCharCode(event.charCode);
      // console.log(inputChar, e.charCode);
         if (!pattern.test(inputChar)) {
         // invalid character, prevent input
             event.preventDefault();
        }
   }
  </code></pre>
  
  <p>On kepress event it restrict user to enter only numbers but problem with this code is backspace, tab keys are not working.So, this code is not as per my expectation...</p>