What steps can be taken to incorporate a validation pattern that restricts the use of only whitespace in input for Angular2?

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To incorporate a validation pattern that restricts the use of only whitespace in input for Angular2, you can follow these steps:

1. Define a regular expression pattern to match the whitespace input. For example:

/^\s*$/

1. Implement the pattern as a custom validator function. Here is an example implementation:

import { AbstractControl, ValidatorFn } from '@angular/forms';

export function noWhitespaceValidator(): ValidatorFn {
  return (control: AbstractControl): {[key: string]: any} | null => {
    const input = control.value;
    const hasWhitespace = input && /^\s*$/.test(input);
    return hasWhitespace ? {'whitespace': {value: input}} : null;
  };
}

1. Use the validator function in a form control or form group. For example:

import { Component } from '@angular/core';
import { FormControl, FormGroup, Validators } from '@angular/forms';
import { noWhitespaceValidator } from './no-whitespace-validator';

@Component({
  selector: 'app-root',
  template: `
    <form [formGroup]="form">
      <input formControlName="input">
      <div *ngIf="form.get('input').hasError('whitespace')">
        Only whitespace characters are not allowed.
      </div>
    </form>
  `
})
export class AppComponent {
  form: FormGroup;

  constructor() {
    this.form = new FormGroup({
      input: new FormControl('', {
        validators: [
          Validators.required,
          noWhitespaceValidator()
        ]
      })
    });
  }
}

In this example, the noWhitespaceValidator is used alongside the required validator to ensure that the input field cannot be empty or contain only whitespace characters. If the input fails the validation, the error message will be displayed in the template.