one-time binding (::) in modern Angular

Angular has no :: syntax and does not need one. Bindings are compiled code with no watcher list, and OnPush with signals limits checks to the components whose data changed.

<h1>{{ ::vm.title }}</h1>
<ul>
  <li ng-repeat="c in ::vm.countries">{{ ::c.name }}</li>
</ul>
<span ng-class="::{ premium: vm.user.premium }">{{ ::vm.user.plan }}</span>

@Component({
  selector: 'app-country-list',
  changeDetection: ChangeDetectionStrategy.OnPush,
  template: `
    <h1>{{ title() }}</h1>
    @for (c of countries(); track c.id) {
      <li>{{ c.name }}</li>
    }
  `,
})
export class CountryListComponent {
  title = input.required<string>();
  countries = input.required<Country[]>();
}

What changes

• Remove the :: prefix; the binding itself stays the same.
• ChangeDetectionStrategy.OnPush skips a component until an input changes, an event fires inside it, or a signal it reads changes.
• Static lists rendered with @for and a track expression are not re-created when nothing changed.

Related

• ng-change / ng-blur / ng-keyup
• ng-disabled / ng-readonly / ng-checked
• ng-src / ng-href / ng-srcset
• ngMessages