How do you conditionally render Login/Logout with isLoggedIn in Vue or Angular?

This tests whether you understand the cost of mounting, unmounting, and re-creating event listeners versus simply toggling CSS visibility. A strong answer uses v-if/v-else or *ngIf when the condition is unlikely to change, because structural directives fully remove the element from the DOM and destroy child component state. It uses v-show or [hidden] for frequent toggles because the node stays in the DOM and only its display property changes. A red flag is claiming the two are identical or always choosing one out of habit.