using a function in *ngIf runs several times instead of once

Question

Template

{{email|json}} - {{user|json}}

Component

isAdmin() {
    console.log(\'         


        

Answer 1

Template methods will almost always be called multiple times. The same is true for *ngFor that it is iterated over multiple times. If you have something that executes an expensive call then you should cache the result and return that either in the method or use ngOnInit to retrieve/calculate the values and set them in your component.

Template code

{{email|json}} - {{user|json}}

Component

export class MyComponent implements OnInit {

    isAdmin: boolean;

    ngOnInit() {
        this.isAdmin = this.bcAuthService.isAdmin();
        console.log('isAdmin: ', this.isAdmin);
    }
}