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TypeScript: Where's My C# Style Object Initializers?

In C#, you’re able to initialize an object while newing it up.

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using System;

public class Program
{
    public static void Main()
    {
        var person = new Person
        {
            GivenName = "John",
            FamilyName = "Doe"
        };

        Console.WriteLine(person.Name); // John Doe
    }
}

public class Person
{
    public string GivenName { get; set; }
    public string FamilyName { get; set; }

    public string Name => $"{GivenName} {FamilyName}";
}

However, this specific syntax is not available in TypeScript. We could simply do it long form:

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class Person {
  givenName: string;
  familyName: string;

  get name(): string { return `${this.givenName} ${this.familyName}`};
}

const person = new Person();
person.givenName = 'John';
person.familyName = 'Doe';

console.log(person.name); // John Doe

Or, you can try something like this:

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// Attribution: This idea is from http://stackoverflow.com/a/14142198/941536
interface Person {
  givenName: string;
  familyName: string;
}

const person: Person = {
  givenName: 'John',
  familyName: 'Doe'
};

Note that the previous code example requires that givenName and familyName must be implemented. If that’s exactly what you want, this works OK.

But, if Person is a class instead and you need getters or other functionality to work, and you’re able to modify this class, it might make sense to use the constructor:

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// Attribution: This idea is from http://stackoverflow.com/a/14226836/941536
class Person {
  constructor(public givenName: string, public familyName: string) {
  }

  get name(): string { return `${this.givenName} ${this.familyName}`};
}

const person = new Person("John", "Doe");

console.log(person.name); // John Doe

Alternatively, the constructor could accept and work with an object instead, as suggested in https://github.com/Microsoft/TypeScript/issues/3895#issuecomment-122046396.


If you’ve got a better idea (that’s preferably still lightweight) let me know in the comments!

This post is licensed under CC BY 4.0 by the author.

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