script.js

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

let string ="";
let array=Array.from(buttons);
array.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;
        }
    })
})