how to detect if a link was clicked when window.onbeforeunload is triggered?

Question

I have window.onbeforeunload triggering properly. It's displaying a confirmation box to ensure the user knows they are navigating (closing) the window and that any unsaved work will be erased.

I have a unique situation where I don't want this to trigger if a user navigates away from the page by clicking a link, but I can't figure out how to detect if a link has been clicked inside the function to halt the function. This is what I have for code:

window.onbeforeunload = function() {
var message = 'You are leaving the page.';

/* If this is Firefox */
if(/Firefox[\/\s](\d+)/.test(navigator.userAgent) && new Number(RegExp.$1) >= 4) {
  if(confirm(message)) {
    history.go();
  } 
  else {
    window.setTimeout(function() {
      window.stop();
    }, 1);
  }
}
/* Everything else */
else {
  return message;
}
}

Answer 1

You're looking for deferred event handling. I'll explain using jQuery, as it is less code:

window._link_was_clicked = false;
window.onbeforeunload = function(event) {
  if (window._link_was_clicked) {
    return; // abort beforeunload
  }
  // your event handling
};

jQuery(document).on('click', 'a', function(event) {
  window._link_was_clicked = true;
});

a (very) poor man's implementation without jQuery's convenient delegation handling could look like:

document.addEventListener("click", function(event) {
  if (this.nodeName.toLowerCase() === 'a') {
    window._link_was_clicked = true;
  }
}, true);

this allows all links on your page to leave without invoking the beforeunload handler. I'm sure you can figure out how to customize this, should you only want to allow this for a specific set of links (your question wasn't particularly clear on that).