react-index-children.tsx

const isElementTextAreaConnected = (x): x is React.SFCElement<typeof TextAreaConnected> =>
    typeof x === "object"
    && typeof x.type !== "string"
    && areComponentsEqual(x.type, TextAreaConnected)

const BlackMagicBoxV2 = ({ children, y = { i: 0, j: 0 } }) => {
    return React.Children.map(children, x => {
        if (typeof x === "object") {
            return isElementTextAreaConnected(x) ?
                React.cloneElement<any, {}>(x, { i: y.j++ }) :
                React.cloneElement(x, {
                    children: BlackMagicBoxV2({ children: x.props.children, y })
                });
        } else {
            return x;
        }
    }) as any;
}