angular - Negating the result of a promise in a guard -

i have working angular2 guard canactivate() calls service isloggedin() , returns promise resolves , route handled appropiately.

however, trying opposite, see when user not logged in, , isn't working.

i tried simple (adding ! operator), hoping work:

@injectable() export class authguard implements canactivate {     constructor(private authservice: authservice) {}      canactivate() {         return !this.authservice.isloggedin();     } } 

however, returns falsey value , route never activates.

this relevant excerpt of isloggedin() function:

isloggedin(): promise<boolean> {   var component = this;   return new promise((resolve, reject) => {              component.queryforuser((user) => {         resolve(user != null);       });     }   }); } 

if user not equal null, logged in , promise resolves true. else, false.

while add parameter specify state looking for, or create isnotloggedin() function, same logic inverted, ask, there way negate value of promise's resolve canactivate()?

return !this.authservice.isloggedin() won't work, because of how js works. this.authservice.isloggedin() promise object , truthy. !this.authservice.isloggedin() false.

instead, promise result should mapped negated result with

canactivate() {     return this.authservice.isloggedin().then(result => !result); } 

or

async canactivate() {     return !(await this.authservice.isloggedin()); } 

the parentheses around await ... optional , used readability.