let input = document.getElementById('inputbox');
let buttons = document.querySelectorAll('button');

let string = "";
let arr =  Array.from(buttons);
arr.forEach(button =>
{
    button.addEventListener('click',(e) =>
    {
        if(e.target.innerHTML == '=')
        {
            string = eval (string);
            input.value = string;
        }
        else if (e.target.innerHTML=='AC')
        {
            string = "";
            input.value = string;
        }
        else if(e.target.innerHTML == 'DEL') {
    string  = string.substring(0, string.length-1);
    input.value = string;
        }
        else{
        string += e.target.innerHTML;
        input.value =string;
        }
        })
    })