window.hyphaChanged = false;
let textarea = document.querySelector('.edit-form__textarea');
let form = document.querySelector('.edit-form');

let warnBeforeClosing = function (ev) {
    if (!window.hyphaChanged) return;
    ev.preventDefault();
    return ev.returnValue = 'Are you sure you want to exit? You have unsaved changes.';
};

textarea.addEventListener('input', function () {
    window.hyphaChanged = true;
});

form.addEventListener('submit', function () {
    window.hyphaChanged = false;
});

window.addEventListener('beforeunload', warnBeforeClosing);