Convert text field to phone field - JS

    const inputField = document.querySelector("#ff_4_input_text");
    inputField.addEventListener("keydown", function (event) {
      if (
        event.key === "Backspace" ||
        event.key === "Delete" ||
        event.key === "ArrowLeft" ||
        event.key === "ArrowRight" ||
        event.key === "ArrowUp" ||
        event.key === "ArrowDown" ||
        event.key === "Tab" ||
        (event.key.startsWith("Num") && event.key.length > 3)
      ) {
        return;
      }
      if (/^\d$/.test(event.key)) {
        const currentValue = event.target.value;
        if (!currentValue.startsWith("+30")) {
          event.target.value = "+30" + currentValue;
        }
      } else {
        event.preventDefault();
      }
    });

    inputField.addEventListener("paste", function (event) {
      const pastedText = (event.clipboardData || window.clipboardData).getData("text");
      if (!/^\d*$/.test(pastedText)) {
        event.preventDefault();
      } else {
        const currentValue = event.target.value;
        event.target.value = "+30" + currentValue;
      }
    });