Property 'X' has no initializer and is not definitely assigned in the constructor

[AhmedElTabarani]

🔎 Search Terms

Property 'X' has no initializer and is not definitely assigned in the constructor

🕗 Version & Regression Information

• This changed between versions ______ and _______
• This changed in commit or PR _______
• This is the behavior in every version I tried, and I reviewed the FAQ for entries about _________
• I was unable to test this on prior versions because _______

⏯ Playground Link

https://www.typescriptlang.org/play/?ts=5.8.0-dev.20250125#code/IYIwzgLgTsDGEAJYBthjAgkgEwOIFMA7fGCAeygH0BGBAbwCgFmEAHKASwDdgJ8FIvDrASpIOAFwJCAVwC2IEggC8CAAwBuJi3bde-DtimyFJDQgD0FhAFEoUCg23NYZQpCgz4FABQBKemcWZggACw4wADowfAgCYlJ8bBx-LWCAXydg3R4+AVj4kn1k7H9A4OCcQtIKGkixCBwAaia0ipDwqMMVLDwiIvIqanq0Ruw25kyg1hkQZGEEAHNYlL9jeUUocvaEKFiZKEIEMIjIwwmETKnQDzhEFDQMKv6aqgAmbeYc-QEIIREGpJpBslKpNNNOLkDEZgaYoOYrAgAHJkWz2RxBVzuaBeQZlRg7XrVXi1N4jcTYFoXYInLrYHrPBIk97ksYXKbZWbzETLMb+dZwz4VPYQA5HWlncZBK5AA

💻 Code

I encountered an inconsistency in the TypeScript compiler when using static properties in abstract classes
The following code produces an error in IdGenerator_1 but not in IdGenerator_2

abstract class IdGenerator_1 {
    private static lastId: number = 0;
    private id: number; // Error

    constructor() {
        this.setGeneratedId();
    }

    private setGeneratedId() {
        IdGenerator_1.lastId++;
        this.id = IdGenerator_1.lastId;
    }

    public getId(): number {
        return this.id;
    }
}

abstract class IdGenerator_2 {
    private static lastId: number = 0;
    private id: number; // No Error

    constructor() {
        IdGenerator_2.lastId++;
        this.id = IdGenerator_2.lastId;
    }

    public getId(): number {
        return this.id;
    }
}

🙁 Actual behavior

The compiler produces an error for IdGenerator_1 but not for IdGenerator_2

🙂 Expected behavior

Both IdGenerator_1 and IdGenerator_2 should compile without errors, as they are functionally identical

Additional information about the issue

No response

[MartinJohns]

Duplicate of #59997.

[typescript-bot]

This issue has been marked as "Duplicate" and has seen no recent activity. It has been automatically closed for house-keeping purposes.