Question

为什么当括号跟随返回时，角度指令不起作用？

app.directive("alert", function () {
  return {
     restrict: "EA",
      template: "<div>Alert!!</div>"
  };
});

但是，当括号与回程相邻时，确实有效：

    GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
            .requestScopes(new Scope(Scopes.DRIVE_APPFOLDER))
            .requestIdToken("685357920901-sfghh9b8heq89b3g1l7gun3csuilur5c.apps.googleusercontent.com")
            .requestEmail()
            .build();



    mGoogleApiClient = new GoogleApiClient.Builder(this)
            .enableAutoManage(this, null)
            .addApi(Auth.GOOGLE_SIGN_IN_API, gso)
            .build();

    mAuth = FirebaseAuth.getInstance();


    mAuthListener = new FirebaseAuth.AuthStateListener() {
        @Override
        public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
            FirebaseUser user = firebaseAuth.getCurrentUser();
            if (user != null) {
                Log.d(TAG, "onAuthStateChanged:signed_in:" + user.getUid());
            } else {
                Log.d(TAG, "onAuthStateChanged:signed_out");
            }
        }
    };

}

@Override
public void onStart() {
    super.onStart();
    mAuth.addAuthStateListener(mAuthListener);
}

@Override
public void onStop() {
    super.onStop();
    if (mAuthListener != null) {
        mAuth.removeAuthStateListener(mAuthListener);
    }
}

private void firebaseAuthWithGoogle(GoogleSignInAccount acct) {
    Log.d(TAG, "firebaseAuthWithGoogle:" + acct.getId());

    AuthCredential credential = GoogleAuthProvider.getCredential(acct.getIdToken(), null);
    mAuth.signInWithCredential(credential)
            .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    Log.d(TAG, "signInWithCredential:onComplete:" + task.isSuccessful());

                    if (!task.isSuccessful()) {
                        Log.d("here", "not");
                        Log.w(TAG, "signInWithCredential", task.getException());
                        Toast.makeText(MainActivity.this, "Authentication failed.",
                                Toast.LENGTH_SHORT).show();
                    }
                    else{
                        Log.d("here", "ohyeah");
                        Toast.makeText(MainActivity.this, "done", Toast.LENGTH_SHORT).show();
                    }
                }
            });
}


public void SignIn(View view) {
    Intent signInIntent = Auth.GoogleSignInApi.getSignInIntent(mGoogleApiClient);
    startActivityForResult(signInIntent, RC_SIGN_IN);

}

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);



    if (requestCode == RC_SIGN_IN) {
        GoogleSignInResult result = Auth.GoogleSignInApi.getSignInResultFromIntent(data);
        Log.d("here", "o   "+result);
        Log.d("here", "o00000       "+result.isSuccess());
        if (result.isSuccess()) {
            // Google Sign In was successful, authenticate with Firebase
            GoogleSignInAccount account = result.getSignInAccount();
            firebaseAuthWithGoogle(account);
            Log.d("here", "success");
        } else {
            Log.d("here", "fail");

        }
    }
}

Answer 1

因为当你刚刚返回被认为不返回undefined时（没有）。您必须在同一行返回一些内容，否则与return;

相同

＆安培;当你在同一行上有它时，它认为你从指令返回了对象（DDO）。

Answer 2

这是因为JavaScript会将return作为单个操作，因为return本身就是一个有效的操作。

第一个例子与

相同

app.directive("alert", function () {
  return;
  {
     restrict: "EA",
      template: "<div>Alert!!</div>"
  };
});

Answer 3

这是javascript中自动逗号插入的经典案例。

当您将支架移动到下一个支架时，编译器会在您的线末端预先插入一个半冒号，认为您已经忘记了它。

app.directive("alert", function () {
  return ;
  {
     restrict: "EA",
      template: "<div>Alert!!</div>"
  };
});

AngularJs支持＆＃34;返回＆＃34;

3 个答案: