What is the method to reference a class instance using a local variable?

class D {
    y = 1;
};

let E = D;

function F(arg2: E){
    arg2.y
};

ERROR in [at-loader] ./src/syntax/colletion-range.ts:10:18 TS2749: 'E' refers to a value, but is being used as a type here.

Answer №1

Assigning a variable to alias the class constructor does not necessarily alias the type as well. When you declare a class, you are creating both a value (the constructor) and a type (the instance type of the class).

If you want to define the type explicitly, you can do so like this:

let B = A;
type B = A;

To access the type of the class stored in B, you can use typeof B. Then, you can obtain the instance type using InstanceType:

class A {
    x = 1;
};

let B = A;

function C(arg1: InstanceType<typeof B>){
    arg1.x
};

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