Ready Resolver Pattern

main.ts

export class SomeAsyncClass {
    private _ready: Promise<void>;
    private _readyResolver: Function;
    
    constructor() {
        this._ready = new Promise(resolve => (this._readyResolver = resolve));
        this.init();
    }
    
    private async init() {
        // Do some async bootstrapping here, then...
        this._readyResolver();
    }  
                            
    public async ready(): Promise<void> {
        return this._ready;
    }                            
}

Means you can succinctly wait for init to complete, i.e.:

const someClass = new SomeAsyncClass();
someClass.ready().then(() => {
// crack on here
});