import { FormGroup, FormBuilder, Validators, FormControl } from '@angular/forms';
export class ReactiveFormComponent implements OnInit {
  private myForm: FormGroup;
  constructor(private fb: FormBuilder) {
    this.createForm();
  }

  ngOnInit() {
  }
  // 创建表单元素
  createForm() {
    this.myForm = this.fb.group({
      username: ['', [Validators.required, Validators.minLength(3), Validators.maxLength(6)]],
      mobile: ['', [Validators.required]],
      password: this.fb.group({
        pass1: [''],
        pass2: ['']
      })
    });
  }
  // 提交表单函数
  postDate() {
    /**
     * valid:是否有效
     * invalid:无效
     * dirty:脏
     * status:状态
     * errors:显示错误
     */
    if(this.myForm.valid){
      console.log(this.myForm.value);
    }
  }
}

<form [formGroup]="myForm" (ngSubmit)="postDate()">
  <div class="form-group">
    <label for="username">用户名:</label>
    <input type="text" placeholder="请输入用户名" class="form-control" id="username" formControlName="username" />
  </div>
  <div class="form-group">
    <label for="mobile">手机号码:</label>
    <input type="text" placeholder="请输入手机号码" class="form-control" id="mobile" formControlName="mobile"/>
  </div>
  <div formGroupName="password" style="border:none;">
    <div class="form-group">
      <label>密码:</label>
      <input type="password" class="form-control" placeholder="请输入密码" formControlName="pass1" />
    </div>
    <div class="form-group">
      <label>确认密码:</label>
      <input type="password" class="form-control" placeholder="请再次输入密码" formControlName="pass2" />
    </div>
  </div>
  <div class="form-group">
    <input type="submit" value="提交" class="btn btn-warning" [disabled]="!myForm.valid" />
  </div>
</form>

**格式**
export function fnName(control:FormControl|FormGroup):any{

}

import { FormControl, FormGroup } from '@angular/forms';
/**
 * 自定义验证器(其实就是一个函数,一个返回任意对象的函数)
 * 传递的参数是当前需要验证的表单的FormControl
 * 通过传递的参数获取当前表单输入的值
 */
export function mobileValidator(control: FormControl): any {
  console.dir(control);
  // 获取到输入框的值
  const val = control.value;
  // 手机号码正则
  const mobieReg = /^(((13[0-9]{1})|(15[0-9]{1})|(18[0-9]{1}))+\d{8})$/;
  const result = mobieReg.test(val);
  return result ? null : { mobile: { info: '手机号码格式不正确' } };
}

createForm() {
  this.myForm = this.fb.group({
    username: ['', [Validators.required, Validators.minLength(3), Validators.maxLength(6)]],
    mobile: ['', [Validators.required, mobileValidator]],
    password: this.fb.group({
      pass1: [''],
      pass2: ['']
    })
  });
}

// 定义一个密码组的验证方法
export function passValidator(controlGroup: FormGroup): any {
  // 获取密码输入框的值
  const pass1 = controlGroup.get('pass1').value as FormControl;
  const pass2 = controlGroup.get('pass2').value as FormControl;
  console.log('你输入的值:', pass1, pass2);
  const isEqule: boolean = (pass1 === pass2);
  return isEqule ? null : { passValidator: { info: '两次密码不一致' } };
}
 

createForm() {
  this.myForm = this.fb.group({
    username: ['', [Validators.required, Validators.minLength(3), Validators.maxLength(6)]],
    mobile: ['', [Validators.required, mobileValidator]],
    password: this.fb.group({
      pass1: [''],
      pass2: ['']
    }, {validator: passValidator})
  });
}

<div class="form-group">
  <label for="username">用户名:</label>
  <input type="text" placeholder="请输入用户名" class="form-control" id="username" formControlName="username" />
  <!-- 当输入框没有访问的时候或者合法的时候不显示 -->
  <div [hidden]="myForm.get('username').valid || myForm.get('username').untouched">
    <p [hidden]="!myForm.hasError('required','username')">用户名必填的</p>
    <p [hidden]="!myForm.hasError('minlength','username')">用户名长度过短</p>
    <p [hidden]="!myForm.hasError('maxlength','username')">用户名长度太长</p>
  </div>
</div>
<div class="form-group">
  <label for="mobile">手机号码:</label>
  <input type="text" placeholder="请输入手机号码" class="form-control" id="mobile" formControlName="mobile"/>
  <div [hidden]="myForm.get('mobile').valid || myForm.get('mobile').untouched">
    <p [hidden]="!myForm.hasError('mobile', 'mobile')">{{myForm.getError('mobile', 'mobile')?.info}}</p>
  </div>
</div>
<div formGroupName="password" style="border:none;">
  <div class="form-group">
    <label>密码:</label>
    <input type="password" class="form-control" placeholder="请输入密码" formControlName="pass1" />
  </div>
  <div class="form-group">
    <label>确认密码:</label>
    <input type="password" class="form-control" placeholder="请再次输入密码" formControlName="pass2" />
  </div>
  <!-- 对于group可以不在外面加一层判断 -->
  <div>
    <p [hidden]="!myForm.hasError('passValidator','password')">
      {{myForm.getError('passValidator','password')?.info}}
    </p>
  </div>
</div>

.ng-touched:not(form),.ng-invalid:not(form) {
  border: 1px solid #f00;
}

.ng-valid:not(form),.ng-untouched:not(form) {
  border: 1px solid #ddd;
}
p{
  color:#f00;
}

 [class.error]="myForm.get('username').invalid && myForm.get('username').touched"