@slebetmen's accepted answer explains well why this doesn't work. In addition to the two patterns presented in that answer, another option is to only access your async properties through a custom async getter. The constructor() can then trigger the async creation of the properties, but the getter then checks to see if the property is available before it uses or returns it.
This approach is particularly useful when you want to initialize a global object once on startup, and you want to do it inside a module. Instead of initializing in your index.js and passing the instance in the places that need it, simply require your module wherever the global object is needed.
Usage
const instance = new MyClass();
const prop = await instance.getMyProperty();
Implementation
class MyClass {
constructor() {
this.myProperty = null;
this.myPropertyPromise = this.downloadAsyncStuff();
}
async downloadAsyncStuff() {
// await yourAsyncCall();
this.myProperty = 'async property'; // this would instead by your async call
return this.myProperty;
}
getMyProperty() {
if (this.myProperty) {
return this.myProperty;
} else {
return this.myPropertyPromise;
}
}
}