symbol interfaces in angular

ng-lifecycle-interfaces.ts

// Somewhere in `@angular/core`:

export const OnInit: unique symbol = Symbol('OnInit');

export interface OnInit {
  [OnInit](): void;
}

// In a component:

import { Component, OnInit } from '@angular/core';

@Component
export class Foo implements OnInit {
  [OnInit](): void {
    // do stuff
  }
}