How to use a class asynchronously in javascript?

I need to write a class that fetch data on creation and then use that data asynchronously. nut not sure how I can use a class that handles data asynchronously in JavaScript?

I need to write a class that fetch data on creation and then use that data asynchronously. something like this. but this code throws error as the instance is not promise

class Features {
  constructor(){
    this.features = null;
    this.fetchFeatures();
   }
   async fetchFeatures () {
     const result = await fetchAllFeatures();
     this.features = result;
   }
}

const featuresInstance = new Features();
featuresInstance.then((res) => console.log(featuresInstance.features));