scroll.js

function smoothScroll(target,duration){
    var target = document.querySelector(target)
    var targetPosition = target.getBoundingClientRect().top;
    var startPosition = window.pageYOffset;
    var distance = targetPosition-startPosition;
    var startTime = null;

    function animation(currentTime){
        if(startTime === null) startTime = currentTime;
        var timeELapsed = currentTime - startTime;
        var run = ease(timeELapsed,startPosition,distance,duration)
        window.scrollTo(0,run);
        if(timeELapsed < duration) requestAnimationFrame(animation)
    }
    function ease(t, b, c, d) {
        t /= d/2;
        if (t < 1) return c/2*t*t + b;
        t--;
        return -c/2 * (t*(t-2) - 1) + b;
    };

    
    requestAnimationFrame(animation);

   
}
var section1 = document.querySelector('.section1');
section1.addEventListener('click',function(){
    smoothScroll('.section2',1000)

})