transform JavaScript object

export function transform(o: any, fn: (obj: any, prop: string, value: any) => any) {
    if (o && typeof o === 'object') {
        Object.keys(o).forEach((k, i) => {
            o[k] = fn.apply(this, [o, k, o[k]])
            if (o[k] && typeof o[k] === 'object') {
                return transform(o[k], fn)
            }
            return o[k]
        })
        return o
    }
    return o
}