angularfire验证功能，用于验证电子邮件是否正在使用

我知道android angularfire提供了类似firebase.auth.getinstances（）的功能，它可以获取并检查任何电子邮件标识符是否与输入字段匹配，以验证电子邮件的可用性。是否有一个web应用程序的等效功能，因为我一直在寻找文档，但没有结果

这就是我到目前为止所拥有的，我想要实现的是能够在继续让用户输入密码之前验证电子邮件

<form novalidate [formGroup]="SignupForm">
  <div *ngIf="!regEmail">
    <div class="form-group w-100">
      <button mat-button type="button" class="btn-google" (click)="authService.GoogleAuth()">
        <i class="fa fa-google"></i>
        Sign up with Google
      </button>
    </div>

    <div class="form-group w-100">
      <button mat-button type="button" class="btn-facebook " (click)="authService.FacebookAuth()">
        <i class="fa fa-facebook"></i>
        Sign up with Facebook
      </button>
    </div>
    <div class="divider w-100">
      <span class="bg-white p-3"><span class="orInner">OR</span></span>
    </div>
    <mat-form-field>
      <input matInput type="email" placeholder="email" formControlName="email" #userEmail>
    </mat-form-field>
    <!--Error codes-->
    <div class="d-flex flex-column align-items-center">
      <div class="form-group w-100">
        <button mat-raised-button type="button" class="w-100" (click)="emailValidate( userEmail.value)">Continue
        </button>
      </div>
    </div>

  </div>

  <div *ngIf="regEmail">
    <mat-form-field>
      <input matInput type="password" placeholder="Password" #userPwd required>
    </mat-form-field>
    <div class="form-group w-100">
      <button mat-raised-button type="button" class="w-100"
        (click)="authService.SignUp( userEmail.value, userPwd.value)">Continue
      </button>
    </div>
  </div>
</form>

您可以使用来检查

signingmethods

是否包含

密码

，因此它类似于

 emailValidate(email) {
    return this.authService.afAuth.auth.fetchSignInMethodsForEmail(email)
    .then((signInMethods)=> {
       var isEmailAvailable=!signInMethods.includes('password');
          if (isEmailAvailable){
               this.regEmail = email;
            }
             else{
           alert('email not available')
          }
    }

---

谢谢这句话让我困了这么久

var isEmailAvailable=！签名方法。包括（“密码”）
 emailValidate(email) {
    return this.authService.afAuth.auth.fetchSignInMethodsForEmail(email)
    .then((signInMethods)=> {
       var isEmailAvailable=!signInMethods.includes('password');
          if (isEmailAvailable){
               this.regEmail = email;
            }
             else{
           alert('email not available')
          }
    }