What is the process for distributing the attributes of objects within an array to various class properties?

I am working on a TypeScript class that includes 2 private properties and an array of objects.

class AssigningProperties {
  private animalType1: string;
  private animalType2: string;

  animals = [
    {
      name: "Bob",
      type: "cat"
    },
    {
      name: "Max",
      type: "dog"
    }
  ];

  constructor() {
    this.animals.forEach(v => console.log(v.name));
  }
}

new AssigningProperties ();

I am trying to assign the values 'cat' and 'dog' to the class properties animalType1 and animalType2, respectively, using the Array.foreach method.

Currently, I can achieve this by accessing the objects through their index like so:

this.animalType1 = this.animals[0].type;
but I believe there might be a more efficient approach. Any suggestions?

View CodeSandBox Example

Answer №1

Your current approach is effective, but for a more streamlined process, consider converting `animalTypes` into an array:

private animalTypes: string[];

Subsequently, utilize the index parameter in the callback function of `forEach` to assign values:

this.animals.forEach((v, i) => v.type = this.animalTypes[i]);

If your intention was to assign `"cat"` to the first entry in `animalTypes` (as demonstrated in your CodeSandbox code), you can do so by:

this.animals.forEach((v, i) => this.animalTypes[i] = v.type);

Regardless of which method you choose, having the type stored in multiple places may lead to maintenance challenges. It's recommended to use getters instead if `animals` should be the single source of truth:

private get animalType1(): string {
 return this.animals[0].type;
}
private get animalType2(): string {
  return this.animals[1].type;
}

Live Copy on the playground

Alternatively, if you opt for the `animalTypes` approach, consider using a Proxy:

interface Animal {
  name: string;
  type: string;
}
class AssigningProperties {
  animals: Animal[] = [
    {
      name: "Bob",
      type: "cat"
    },
    {
      name: "Max",
      type: "dog"
    }
  ];
  private animalTypes = new Proxy<Animal[]>(this.animals, {
    get(target, propName) {
      if (propName in target) {
        return Reflect.get(target, propName).type;
      }
      return undefined;
    }
  });
}

Live Copy on the playground

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