state inside urls

url.js

import {useRouter} from "next/router";


//...


const router = useRouter();
const {router_steep} = router.query
const steep = (isNaN(+router_steep) || +router_steep < 0) ? 0 
                  : +router_steep;
const setSteep = (router_steep: number) => router.push(
          `/https://your.website.com?router_steep=${router_steep}`, 
                            undefined, {shallow: true});

//...