Tslint: Rule request: empty-constructor

[JoshuaKGoldberg]

TypeScript code being linted

class Counter {
    private count: number = 0;

    public constructor() { }

    public increase(): number {
        return this.count += 1;
    }
}

Actual behavior

No complaints under tslint:recommended.

Expected behavior

The constructor does nothing and should be removed. There's no complaint saying this.

Folks new to classes / TypeScript will sometimes add constructors because they think they're necessary no matter what.

[JoshuaKGoldberg]

Another thing to look out for as an option (should just initialize via private count: number = 0;):

class Counter {
    private count: number;

    public constructor() {
        this.count = 0;
    }

    public increase(): number {
        return this.count += 1;
    }
}

[vpanjganj]

@JoshuaKGoldberg isn't this covered by [tslint] block is empty [no-empty] rule anyway?

[JoshuaKGoldberg]

@vpanjganj technically yes, but not everybody enables no-empty.

[ghost]

And what about the following example? Isn't it unnecessary as well?

constructor() {
    super();
}

[JoshuaKGoldberg]

@asmironov yup, that's correct!

[Bublade]

@asmironov @JoshuaKGoldberg isnt something like this unnecessary as well?

constructor(requiredParam: string) {
    super(requiredParam);
}

[JoshuaKGoldberg]

Ah, this rule was added in #3647. It only handles the case of a constructor with an empty body.

@Bublade that's correct! If you'd like to file a new issue, that'd be great.

[elharony]

@JoshuaKGoldberg It seems like a +6 yrs concern since #67 🤔
As mentioned in the old issue, to get around this, you can add an empty comment

constructor() {
  //
}

For new devs who write in TypeScript and came across this comment, just listen to @JoshuaKGoldberg 's tip, and delete "empty" constructor, if it's empty, then you don't need it, and removing redundant stuff is a great benefit we get by using a linter. Do NOT try to skip/ignore/stop every linting rule to "pass" it!