Async/await Class Constructor

Async operations in init(), not just for breakfast

The init() method shines through for accomplishing asynchronous operations post-construction when you're in a tight spot due to language constraints.

class MyClass {
  constructor() {
    // Synchronous setup happens here
  }

  async init() {
    this.data = await loadData(); // Fetching data asynchronously
  }
}

// Usage:
const myInstance = new MyClass();
myInstance.init().then(() => {
  // Your instance is ready for action, roll the drums!
});
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TypeScript and the art of typing safely

In TypeScript, secure type safety like a vault by explicitly asserting the class type using async constructor pattern within async factory methods.

class MyClass {
  data: Data;

  private constructor(data: Data) {
    this.data = data;
  }

  static async build(): Promise<MyClass> {
    const data = await loadData(); // Baking the data pie
    return new MyClass(data); // Here's your piece of the pie!
  }
}
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The builder pattern, a story of step-by-step construction

Builder pattern: Offers a safe haven for intricate object construction by enabling step-by-step configuration, working with asynchronous operations gorgeously.

class MyClassBuilder {
  constructor() {
    this.instance = new MyClass();
  }

  async withData() {
    this.instance.data = await loadData(); // Fetching data like a pro
    return this; // Enables chaining, just like a goldsmith
  }

  build() {
    return this.instance; // Behold the fully assembled object!
  }
}
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Visualization

The class constructor bears resemblance to the foundation of a house:

Async/Await in Constructor
| Foundation (😴) | Build House (🏗️) |

The tale of two workflows:

Without async/await: Try to build the house 🏗️ instantly after laying the foundation 😴 — it's like building on half-set Jell-O.

| Laying Foundation (😴) | Building House (🏗️) |
| -------------- | ------------------- |
| Immediate Start        | 🚧 Watch for falling bricks!  |

With async/await: Allow your foundation 😴 to set (resolve) before commencing the build 🏗️ — ensuring a rock-solid and stable structure.

| Laying Foundation (😴) | Await (⏳) | Building House (🏗️) |
| -------------- | ---------- | ------------------- |
| Commence Promise     | Promise settles like a cat on a warm laptop | Safe to build 🏠 |

It's the sequence of ORDER and TIMING that secures your code's edifice!

Sync Constructor       | Async Constructor                 
-------------------- | --------------------------------
🚧 Will it stand?   | 🛠️ Built to withstand gusts of code

### Ensuring the async constructor doesn't ghost you

Keep a tab on **undefined return values**: Make certain that your async workflows within constructor patterns do not lead to instances that are **undefined** or **half-baked**.

```javascript
// Factoring an error handling within the async static method
class MyClass {
  static async build() {
    try {
      const data = await loadData();
      return new MyClass(data); // Data pie's ready!
    } catch (error) {
      console.error('Oops, burned the data pie:', error);
      throw error; // Let the caller handle the charred pie
    }
  }
}

Error handling, your safety net

Slip into error handling mode: Incorporate try-catch clad safety harnesses within your async crusades.

Seamless inheritance and factory production

Inheritance: Steer clear from direct usage of async constructors during class extension. It can tangle with inheritance patterns and turn super() into super complicated.

class ParentClass {
  data;

  constructor(data) {
    this.data = data;
  }
}

class ChildClass extends ParentClass {
  async init() {
    // Additional async initialization, because why not!
    this.extraData = await loadExtraData();
  }
}
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Factory functions: Match Object.create() with a trusted factory function to spawn an object instance and subsequently populate it asynchronously.

function createMyClassAsync() {
  const instance = Object.create(MyClass.prototype);
  
  return loadData().then(data => {
    instance.data = data; // Instance is now data rich!
    return instance;
  });
}
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Decorating your code, not the Christmas tree!

Decorators: When you can't intrude a class directly, decorators can sheathe a constructor bringing async initialization capabilities to the fore. It's not just used in satin and lace!

function withAsyncInit(originalConstructor) {
  return function (...args) {
    const instance = new originalConstructor(...args);
    instance.init && instance.init(); // Spinning the async magic
    return instance;
  };
}
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On mixins and async considerations

Mixins: These gems can help manage async operations within object compositions. Be sure that async antics wrapped within mixins are holstered securely and appropriately awaited.