Combining the Parameter Properties shorthand with Destructuring in TypeScript

Question

EDIT

I logged an issue on TypeScript's Github repo and they're accepting PRs for implementing it.

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In TypeScript, when we want to automatically create properties in our class from the constructor definition, we can take advantage of the Parameter Properties shorthand, e.g:

class Person {
    constructor(public firstName : string, public lastName : number, public age : number) {

    }
}

And then, the transpiled Javascript will be:

var Person = (function () {
    function Person(firstName, lastName, age) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.age = age;
    }
    return Person;
})();

---

But if we want to receive an object in our constructor, it would be something like:

interface IPerson {
    firstName : string,
    lastName : string,
    age: number
}

class Person {
    constructor(person : IPerson) {
        this.firstName = person.firstName;
        this.lastName = person.lastName;
        this.age = person.age;
    }
}

Since TypeScript 1.5, we can take advantage of destructuring, e.g:

class Person {
    constructor({firstName, lastName, age} : {firstName: string, lastName: string, age: number}) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.age = age;
    }
}

---

Question: How to combine the Parameter Properties shorthand and Destructuring in TypeScript?

I've tried to define public before the object definition, e.g:

class Person {
    constructor(public {firstName, lastName, age} : {firstName: string, lastName: string, age: number}) {

    }
}

Tried to define it before each variable, e.g:

class Person {
    constructor({public firstName, public lastName, public age} : {firstName: string, lastName: string, age: number}) {

    }
}

But I had no success. Any thoughts?

Answer 1

If you have access to Object.assign, this works:

class PersonData {
  firstName: string
  constructor(args : PersonData) {
    Object.assign(this, args)
  }
}

class Person extends PersonData{}

But note new instances will be populated by anything in args--you can't strip out just the keys you want to use.