pandaa

section{
    display: none;
}
.block{
    display: block;
}

let m = document.getElementsByTagName('section');


let i = 0;
let y = 0;

loop(i);

function loop(i){

    m[y].classList.remove('block');
    m[i].classList.add('block');


    let buttons = m[i].getElementsByTagName('button');

    if (buttons.length > 1) {
        if (buttons[0].innerHTML == 'Back') {
            buttons[0].onclick = function () {
                console.log('back');
                y = i;
                i--;
                loop(i);
            }
        }
        if (buttons[1].innerHTML == 'Next') {
            buttons[1].onclick = function () {
                console.log('next');
                y = i;
                i++;
                loop(i);
            }
        }
    }else{
        if (buttons[0].innerHTML == 'Next') {
            buttons[0].onclick = function () {
                console.log('next');
                y = i;
                i++;
                loop(i);
            }
        }
        if (buttons[0].innerHTML == 'Back') {
            buttons[0].onclick = function () {
                console.log('back');
                y = i;
                i--;
                loop(i);
            }   
        }
    }

}