Applying RegEx

My JavaScript Code:

    document.getElementById("phoneNum").addEventListener("input", (event) => {
    const regex = /^\(?\d{3})\)?[-. ]?(\d{4})$/g;
    const input = document.querySelector(".phoneFormat");
    const format = input.value;
    const phone = input.value;
    const found = regex.test(phone);
    if (!found && phone.length) {
        input.classListList.add("invalid");
        format.classList.add("block");
    } else{
        input.classList.remove("invalid");
        format.classList.remove("block");
    }
});

document.getElementById("phoneForm").addEventListener("submit", (event) =>{
    event.preventDefault();
    const input = document.getElementById("phoneNum");
    const regex = /[()-. ]/g;
    const savedPhoneNum = input.value.replaceAll(regex, "");
    console.log(savedPhoneNum);
});