Not operation with async pipes in Angular 4

You can use with pipes.To make it work you need to write like this with (). cause pipe is 2 operation so for angular its 'false | async'

<h3 *ngIf="!(dataReadyObs | async)"> Please wait ... </h3>

another approach is to use this is more safely

<h3 *ngIf="(dataReadyObs | async) === false"> Please wait ... </h3>

The way how todo that is following:

<h3 *ngIf="(dataReadyObs | async) === false"> Please wait ... </h3>

Because !(dataReadyObs | async) will produce tslint error at least

See the problem with negating async

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