webdev-power-kit/dist/browser/prevent-close/index.js

A powerful toolkit that simplifies access to browser features like clipboard, notifications, battery, vibration, and more — perfect for modern web developers.

let listenerAttached = false;
let currentMessage = "Are you sure you want to leave? Changes may not be saved.";
/**
 * Enables the tab close or refresh warning popup.
 * @param message Optional custom message for the prompt.
 */
export function enablePreventClose(message) {
    if (listenerAttached)
        return;
    listenerAttached = true;
    if (message)
        currentMessage = message;
    window.addEventListener("beforeunload", beforeUnloadHandler);
}
function beforeUnloadHandler(e) {
    e.preventDefault();
    e.returnValue = currentMessage; // Most browsers use this for legacy
}
/**
 * Disables the warning popup and allows normal tab closing.
 */
export function disablePreventClose() {
    if (!listenerAttached)
        return;
    window.removeEventListener("beforeunload", beforeUnloadHandler);
    listenerAttached = false;
}