It's been a while since the constructor shorthand was introduced, and it's really useful. Now I can write this:

class Dog {
  constructor(
    public age: number,
    public weight: number,
  ) {}
}

instead of this:

class Dog {
  public age: number
  public weight: number

  constructor(
    age: number,
    weight: number,
  ) {
    this.age = age
    this.weight = weight
  }
}

And it works even better for more complex classes.

I wonder if there is some shorthand for class constructor with named parameters (using object destructing)? I think new Dog({age: 3, weight: 8}) is much clearer than new Dog(3, 8). No chance of misplacing the argument positions. But class definition for it looks really ugly:

class Dog {
  // 1. declare properties
  public age: number
  public weight: number

  constructor({
    // 2. object destructing
    age,
    weight,
  }: {
    // 3. declare object type
    age: number,
    weight: number,
  }) {
    // 4. assign values
    this.age = age
    this.weight = weight
  }
}
// x4 duplicates, no DRY at all

It's been a while since the constructor shorthand was introduced, and it's really useful. Now I can write this:

class Dog {
  constructor(
    public age: number,
    public weight: number,
  ) {}
}

instead of this:

class Dog {
  public age: number
  public weight: number

  constructor(
    age: number,
    weight: number,
  ) {
    this.age = age
    this.weight = weight
  }
}

And it works even better for more complex classes.

I wonder if there is some shorthand for class constructor with named parameters (using object destructing)? I think new Dog({age: 3, weight: 8}) is much clearer than new Dog(3, 8). No chance of misplacing the argument positions. But class definition for it looks really ugly:

class Dog {
  // 1. declare properties
  public age: number
  public weight: number

  constructor({
    // 2. object destructing
    age,
    weight,
  }: {
    // 3. declare object type
    age: number,
    weight: number,
  }) {
    // 4. assign values
    this.age = age
    this.weight = weight
  }
}
// x4 duplicates, no DRY at all

• typescript
• object-destructuring
• typescript-class

• You might be looking for AssignCtor from here, as shown in this playground link. It works because all you're doing is assigning the properties of the constructor argument to the instance. If that meets your needs I'll write an answer or close as a duplicate. If not, what am I missing? – jcalz Commented 2 hours ago

1 Answer 1

No there is not and probably never will.

Property definition at the constructor level are called Parameter properties.

Those parameter properties are one of those deviation where typescript isn't just typing over JS but also generate some code.

class Dog {
  constructor(
    public age: number,
    public weight: number,
  ) {}
}

generates the following JS

class Dog {
    age;
    weight;
    constructor(age, weight) {
        this.age = age;
        this.weight = weight;
    }
}

What you're asking for new Dog({age: 3, weight: 8}) & new Dog(3, 8) are wildly differnt.

One is an object that has no meaning in JS and the other is what happens at runtime.

Beside a few exceptions TS isn't meant to generate code for you.