https://coryrylan.com/blog/angular-2-form-builder-and-validation-management

<!DOCTYPE html>
<html>

  <head>
    <title>Angular 2+ Form Builder and Validation</title>
    <script src="https://unpkg.com/core-js/client/shim.min.js"></script>
    <script src="https://unpkg.com/zone.js@0.8.4?main=browser"></script>
    <script src="https://unpkg.com/systemjs@0.19.39/dist/system.src.js"></script>
    <script src="systemjs.config.js"></script>
    <script>
      System.import('main.js').catch(function(err){ console.error(err); });
    </script>
    <style>
      body {
        font-family: "HelveticaNeue-Light", "Helvetica Neue Light", "Helvetica Neue", Helvetica, Arial, "Lucida Grande", sans-serif; 
        font-weight: 300;
      }
    </style>
    <link rel="stylesheet" href="styles.css" />
  </head>

  <body>
    <demo-app>Loading...</demo-app>
  </body>
</html>

import { Component } from '@angular/core';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';

import { ValidationService } from 'app/validation.service';

@Component({
  selector: 'demo-app',
  templateUrl: 'app/app.component.html'
})
export class AppComponent {
  userForm: any;
  
  constructor(private formBuilder: FormBuilder) {
      
    this.userForm = this.formBuilder.group({
      'name': ['', Validators.required],
      'email': ['', [Validators.required, ValidationService.emailValidator]],
      'profile': ['', [Validators.required, Validators.minLength(10)]]
    });
    
    console.log(this.userForm);
  }
  
  saveUser() {
    if (this.userForm.dirty && this.userForm.valid) {
      alert(`Name: ${this.userForm.value.name} Email: ${this.userForm.value.email}`);
    }
  }
}


<form [formGroup]="userForm" (submit)="saveUser()">
  <label for="name">Name</label>
  <input formControlName="name" id="name" />
  <control-messages [control]="userForm.controls.name"></control-messages>

  <label for="email">Email</label>
  <input formControlName="email" id="email" />
  <control-messages [control]="userForm.controls.email"></control-messages>

  <label for="profile">Profile Description</label>
  <textarea formControlName="profile" id="profile"></textarea>
  <control-messages [control]="userForm.controls.profile"></control-messages>

  <button type="submit" [disabled]="!userForm.valid">Submit</button>
</form>

export class ValidationService {
    static getValidatorErrorMessage(validatorName: string, validatorValue?: any) {
        let config = {
            'required': 'Required',
            'invalidCreditCard': 'Is invalid credit card number',
            'invalidEmailAddress': 'Invalid email address',
            'invalidPassword': 'Invalid password. Password must be at least 6 characters long, and contain a number.',
            'minlength': `Minimum length ${validatorValue.requiredLength}`
        };

        return config[validatorName];
    }

    static creditCardValidator(control) {
        // Visa, MasterCard, American Express, Diners Club, Discover, JCB
        if (control.value.match(/^(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{14}|6(?:011|5[0-9][0-9])[0-9]{12}|3[47][0-9]{13}|3(?:0[0-5]|[68][0-9])[0-9]{11}|(?:2131|1800|35\d{3})\d{11})$/)) {
            return null;
        } else {
            return { 'invalidCreditCard': true };
        }
    }

    static emailValidator(control) {
        // RFC 2822 compliant regex
        if (control.value.match(/[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?/)) {
            return null;
        } else {
            return { 'invalidEmailAddress': true };
        }
    }

    static passwordValidator(control) {
        // {6,100}           - Assert password is between 6 and 100 characters
        // (?=.*[0-9])       - Assert a string has at least one number
        if (control.value.match(/^(?=.*[0-9])[a-zA-Z0-9!@#$%^&*]{6,100}$/)) {
            return null;
        } else {
            return { 'invalidPassword': true };
        }
    }
}

import { Component, Input } from '@angular/core';
import { FormGroup, FormControl } from '@angular/forms';
import { ValidationService } from './validation.service';

@Component({
  selector: 'control-messages',
  template: `<div *ngIf="errorMessage !== null">{{errorMessage}}</div>`
})
export class ControlMessagesComponent {
  @Input() control: FormControl;
  constructor() { }

  get errorMessage() {
    for (let propertyName in this.control.errors) {
      if (this.control.errors.hasOwnProperty(propertyName) && this.control.touched) {
        return ValidationService.getValidatorErrorMessage(propertyName, this.control.errors[propertyName]);
      }
    }
    
    return null;
  }
}

html {
  font-family: sans-serif;
}

form {
  padding: 10px;
  max-width: 320px;
}

label {
  margin-top: 16px;
  display: block;
}

input, button {
  display: block;
}

input, textarea {
    display: block;
    width: 100%;
    height: 27px;
    padding: 2px 12px;
    font-size: 14px;
    color: #555;
    background-color: #fff;
    background-image: none;
    border: 1px solid #ccc;
    border-radius: 4px;
}

textarea {
  min-height: 100px;
  padding: 12px;
}

button {
  margin-top: 4px;
  color: #fff;
  background-color: #337ab7;
  border: 1px solid #2e6da4;
  border-radius: 3px;
  padding: 4px 8px;
  font-size: 1em;
  font-weight: 300;
}

button[disabled] {
  background-color: #337ab7;
  border-color: #2e6da4;
  opacity: .65;
  cursor: not-allowed;
}

control-messages div {
  color: #E82C0C;
  margin: 6px 0;
}

/**
 * WEB ANGULAR VERSION
 * (based on systemjs.config.js in angular.io)
 * System configuration for Angular samples
 * Adjust as necessary for your application needs.
 */
(function (global) {
  System.config({
    // DEMO ONLY! REAL CODE SHOULD NOT TRANSPILE IN THE BROWSER
    transpiler: 'ts',
    typescriptOptions: {
      // Copy of compiler options in standard tsconfig.json
      "target": "es5",
      "module": "commonjs",
      "moduleResolution": "node",
      "sourceMap": true,
      "emitDecoratorMetadata": true,
      "experimentalDecorators": true,
      "lib": ["es2015", "dom"],
      "noImplicitAny": true,
      "suppressImplicitAnyIndexErrors": true
    },
    meta: {
      'typescript': {
        "exports": "ts"
      }
    },
    paths: {
      // paths serve as alias
      'npm:': 'https://unpkg.com/'
    },
    // map tells the System loader where to look for things
    map: {
      // our app is within the app folder
      'app': 'app',

      // angular bundles
      '@angular/animations': 'npm:@angular/animations/bundles/animations.umd.js',
      '@angular/animations/browser': 'npm:@angular/animations/bundles/animations-browser.umd.js',
      '@angular/core': 'npm:@angular/core/bundles/core.umd.js',
      '@angular/common': 'npm:@angular/common/bundles/common.umd.js',
      '@angular/common/http': 'npm:@angular/common/bundles/common-http.umd.js',
      '@angular/compiler': 'npm:@angular/compiler/bundles/compiler.umd.js',
      '@angular/platform-browser': 'npm:@angular/platform-browser/bundles/platform-browser.umd.js',
      '@angular/platform-browser/animations': 'npm:@angular/platform-browser/bundles/platform-browser-animations.umd.js',
      '@angular/platform-browser-dynamic': 'npm:@angular/platform-browser-dynamic/bundles/platform-browser-dynamic.umd.js',
      '@angular/http': 'npm:@angular/http/bundles/http.umd.js',
      '@angular/router': 'npm:@angular/router/bundles/router.umd.js',
      '@angular/router/upgrade': 'npm:@angular/router/bundles/router-upgrade.umd.js',
      '@angular/forms': 'npm:@angular/forms/bundles/forms.umd.js',
      '@angular/upgrade': 'npm:@angular/upgrade/bundles/upgrade.umd.js',
      '@angular/upgrade/static': 'npm:@angular/upgrade/bundles/upgrade-static.umd.js',

      // other libraries
      'rxjs':                      'npm:rxjs@5.5.2',
      'rxjs/operators':            'npm:rxjs@5.5.2/operators/index.js',
      'tslib':                     'npm:tslib/tslib.js',
      'angular-in-memory-web-api': 'npm:angular-in-memory-web-api@0.4/bundles/in-memory-web-api.umd.js',
      'ts':                        'npm:plugin-typescript@5.2.7/lib/plugin.js',
      'typescript':                'npm:typescript@2.4.2/lib/typescript.js',

    },
    // packages tells the System loader how to load when no filename and/or no extension
    packages: {
      app: {
        main: './main.ts',
        defaultExtension: 'ts',
        meta: {
          './*.ts': {
            loader: 'systemjs-angular-loader.js'
          }
        }
      },
      rxjs: {
        defaultExtension: 'js'
      }
    }
  });

})(this);

/*
Copyright 2016 Google Inc. All Rights Reserved.
Use of this source code is governed by an MIT-style license that
can be found in the LICENSE file at http://angular.io/license
*/

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';

import { AppModule } from './app/app.module';

const platform = platformBrowserDynamic();
platform.bootstrapModule(AppModule);

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { RouterModule } from '@angular/router';

import { AppComponent } from './app.component';
import { ControlMessagesComponent } from './control-messages.component';
import { ValidationService } from './validation.service';

@NgModule({
  imports: [
    BrowserModule,
    ReactiveFormsModule
  ],
  declarations: [
    ControlMessagesComponent,
    AppComponent
  ],
  providers: [ ValidationService ],
  bootstrap: [ AppComponent ]
})
export class AppModule {
}

{
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "moduleResolution": "node",
    "sourceMap": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "removeComments": false,
    "noImplicitAny": true,
    "suppressImplicitAnyIndexErrors": true
  }
}

var templateUrlRegex = /templateUrl\s*:(\s*['"`](.*?)['"`]\s*)/gm;
var stylesRegex = /styleUrls *:(\s*\[[^\]]*?\])/g;
var stringRegex = /(['`"])((?:[^\\]\\\1|.)*?)\1/g;

module.exports.translate = function(load){
  if (load.source.indexOf('moduleId') != -1) return load;

  var url = document.createElement('a');
  url.href = load.address;

  var basePathParts = url.pathname.split('/');

  basePathParts.pop();
  var basePath = basePathParts.join('/');

  var baseHref = document.createElement('a');
  baseHref.href = this.baseURL;
  baseHref = baseHref.pathname;

  if (!baseHref.startsWith('/base/')) { // it is not karma
    basePath = basePath.replace(baseHref, '');
  }

  load.source = load.source
    .replace(templateUrlRegex, function(match, quote, url){
      var resolvedUrl = url;

      if (url.startsWith('.')) {
        resolvedUrl = basePath + url.substr(1);
      }

      return 'templateUrl: "' + resolvedUrl + '"';
    })
    .replace(stylesRegex, function(match, relativeUrls) {
      var urls = [];

      while ((match = stringRegex.exec(relativeUrls)) !== null) {
        if (match[2].startsWith('.')) {
          urls.push('"' + basePath + match[2].substr(1) + '"');
        } else {
          urls.push('"' + match[2] + '"');
        }
      }

      return "styleUrls: [" + urls.join(', ') + "]";
    });

  return load;
};