Extract Props from given ComponentClass object

a.ts

import * as React from 'react';

// Type utilities
type DiffKey<T extends string, U extends string> = (
    & {[P in T]: P } // (1)
    & {[P in U]: never } // (2)
    & { [x: string]: never } // (3)
)[T]; // (4)
type Omit<T, K extends keyof T> = Pick<T, DiffKey<keyof T, K>>;

// Target type extracted from ComponentClass
type Props = {
    x: string
};

// Assuming ComponentClass C is given from somewhere else.
const C : React.ComponentClass<Props> = {} as React.ComponentClass<Props>;
const c = new C({x: 'aaa'});
type T = Omit<typeof c.props, 'children'>;

// T is equivalent to Props
const a : T = {
    x: 'xxx',
};