accessing static member from non-static function in typescript

Question

I am trying to access a static member from a non-static function in the class, and I get an error saying

Static member cannot be accessed off an instance variable

this is how my code looks -

class myClass {
  public static testStatic: number = 0;
  public increment(): void {
    this.testStatic++;
  }
}

From what I understand of static members/methods, we shouldn't access non-static members in static functions, but vice-versa should be possible. the static member is already created and is valid, so why can't I access from my non-static method?

Ryan Cavanaugh · Accepted Answer · 2014-03-19 19:50:13Z

18

Access static members from inside the class the same way you would from outside the class:

class myClass {
  public static testStatic: number = 0;
  public increment(): void {
    myClass.testStatic++;
  }
}

answered Mar 19, 2014 at 19:50

Ryan Cavanaugh

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2 Comments

Renra Over a year ago

It works but it's not a very good practice. Typescript should have a keyword for that. Something like static:: in php. The reason is you're duplicating the name of your class like this. Basically every instance should know its class, right?

Ryan Cavanaugh Over a year ago

I don't see why it's needed for classes any more than it's needed for anything else. There isn't a keyword for the name of the enclosing function, the name of the enclosing module, etc.

Renra · Accepted Answer · 2015-03-25 11:59:27Z

2

I personally prefer something in the spirit of:

class myClass{
    public static testStatic: number = 0;
    private class;

    constructor(){
        this.class = myClass;
    }

    public increment(): void {
        this.class.testStatic++;
    }
}

One cool thing is that typescript is actually allowing me to use 'class' as a variable.

answered Mar 25, 2015 at 11:59

Renra

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1 Comment

Renra Over a year ago

It is still duplication, but duplication in one place only - the constructor.

Eugenio · Accepted Answer · 2018-01-23 16:53:20Z

1

For allowing inheritance you must use inside a instance method in order to don't repeat className:

<typeof ParentClass>this.constructor

See the Update section in this answer: https://stackoverflow.com/a/29244254/1936549

answered Jan 23, 2018 at 16:53

Eugenio

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