how to remove properties via mapped type in TypeScript

Question

Here is the code

class A {
    x = 0;
    y = 0;
    visible = false;
    render() {

    }
}

type RemoveProperties = {
    readonly [P in keyof T         


        

Answer 1

You can use the same trick as the Omit type uses:

// We take the keys of P and if T[P] is a Function we type P as P (the string literal type for the key), otherwise we type it as never. 
// Then we index by keyof T, never will be removed from the union of types, leaving just the property keys that were not typed as never
type JustMethodKeys = ({[P in keyof T]: T[P] extends Function ? P : never })[keyof T];  
type JustMethods = Pick>;