Converter

function solve() {

    let menu = document.getElementById("selectMenuTo");
    menu.appendChild(document.createElement("option"));
    menu.appendChild(document.createElement("option"));
    menu.children[1].value = "binary";
    menu.children[1].textContent = "Binary";

    menu.children[2].value = "hexadecimal";
    menu.children[2].textContent = "Hexadecimal";
   document.querySelector("button").addEventListener("click", () => {

    let number = document.getElementById("input").value;
    let to = document.getElementById("selectMenuTo").value;

            if(number && to == "hexadecimal"){
        document.getElementById("result").value = result =
                            (+number).toString(16).toUpperCase();
            }else if (number && to == "binary"){
        document.getElementById("result").value = result =
                                (+number).toString(2);
            }
   });
}