scripts.js

if (window.addEventListener) { // Mozilla, Netscape, Firefox
    window.addEventListener('load', WindowLoad, false);
} else if (window.attachEvent) { // IE
    window.attachEvent('onload', WindowLoad);
}

function WindowLoad(event) {
    let anchorlinks = document.querySelectorAll('a[href^="#"]')
 
    for (let item of anchorlinks) { // relitere 
        item.addEventListener('click', (e)=> {
            let hashval = item.getAttribute('href')
            let target = document.querySelector(hashval)
            target.scrollIntoView({
                behavior: 'smooth',
                block: 'start'
            })
            history.pushState(null, null, hashval)
            e.preventDefault()
        })
    }
}