title: Regular expression to match Phone number Using Angular reactive form pattern
body: <p>I am trying to validate the phone number using regular expression in angular. Using a regex from this reference <a href="https://stackoverflow.com/questions/16699007/regular-expression-to-match-standard-10-digit-phone-number">Regex Ref</a> which suites my requirements.</p>
  <p>The regex in the controls pattern is not working, getting this error <code>Cannot read property 'get' of undefined</code> -</p>
  <pre><code>this.userForm = this._formBuilder.group({
      firstName: new FormControl('', [
          Validators.required,
          Validators.pattern('^[a-zA-Z ]{1,30}$')
      ]),
      lastName: new FormControl('', [
          Validators.required,
          Validators.pattern('^[a-zA-Z ]{1,30}$')
      ]),
      email: new FormControl('', [
          Validators.required,
          Validators.pattern(
              '[A-Za-z0-9._%-]+@[A-Za-z0-9._%-]+\\.[a-z]{2,3}'
          )
      ]),
      phoneNumber: new FormControl('', [
          Validators.required,
          Validators.pattern(
              '^(+d{1,2}s?)?1?-?.?s?(?d{3})?[s.-]?d{3}[s.-]?d{4}$' // not working
          )
      ]),
      notes: new FormControl(''),
  })
  </code></pre>