app.js

(function(){
    const buttons=document.querySelectorAll(".counterbutton")
    let count=0;
    buttons.forEach(function(button) {
    button.addEventListener('click',function(){
        if(button.classList.contains("nextbtn")){
            count++;
        }
        else if (button.classList.contains("prevbtn")){
            count--;
        }
        const counter=document.querySelector('#counter')
        counter.textContent=count;
        if(count<0)
        {
            counter.style.color='red';
        }
        else if(count>0)
        {
            counter.style.color='green';
        }
        else{
            counter.style.color='black'
        }
    })
    });
}) ()