turn off event listener after triggered once

Question

I have a script that triggers a popover box which offers a free download. It triggers when a user's mouse leaves the page (obviously not for mobile - I already have a working solution for that). In my script I set a cookie to deactivate the script for 30 minutes, and that part works; if I refresh the page the popover doesn't show again.

The problem is that if someone closes the popover box, and haven't refreshed the page (or navigated to another page on the site), the popover occurs every time the mouse moves out of the page.

I am using a function that sets the event, but I can't make it only fire once. (The Wordpress site I am working on is using jquery ver=1.10.2.)

My Javascript:

if (document.cookie.indexOf('somecookiename') != -1) {
  function addEvent(obj, evt, fn) {
    if (obj.addEventListener) {
      obj.addEventListener(evt, fn, false);
    } else if (obj.attachEvent) {
      obj.attachEvent("on" + evt, fn);
    }
  }
};
jQuery(document).ready(function($) {
  if (document.cookie.indexOf('somecookiename') == -1) {
    //var thirtyminutes = 1000*60*30;
    var thirtyminutes = 1000 * 60;
    var expires = new Date((new Date()).valueOf() + thirtyminutes);
    document.cookie = "somecookiename;expires=" + expires.toUTCString();

    addEvent(document, "mouseout", function(e) {
      e = e ? e : window.event;
      var from = e.relatedTarget || e.toElement;
      if (!from || from.nodeName == "HTML") {
        document.getElementById("preview-download").style.display = "block";
        document.getElementById("back-shader").style.display = "block";
      }
    });
  }
});

function showhide(id) {
  if (document.getElementById) {
    obj = document.getElementById(id);
    if (obj.style.display == "none") {
      obj.style.display = "";
    } else {
      obj.style.display = "none";
    }
  }
}

The HTML:

<div id="back-shader" class="popover2">
  <div id="preview-download" class="popover2">
    <h4>BEFORE YOU GO:</h4>
    <h5>Download A Free Preview....</h5>
    <a href="http://website.com/document.pdf" id="preview-pdf">Download Now</a>
    <a href="#" id="closer" onclick="showhide('back-shader'); return(false);"></a>
  </div>
</div>

The CSS:

#back-shader,
#preview-download {
  display: none;
}

It may be something simple, but I am not a javascript expert. Your help, as always, is appreciated.

Answer 1

The easiest way is removing the event listener using removeEventListener :

document.addEventListener("mouseout", function handler(e) {
    e.currentTarget.removeEventListener(e.type, handler);
    /* whatever */
});

 document.addEventListener("click", function handler(e) { e.currentTarget.removeEventListener(e.type, handler); alert('Only once'); });

 Click somewhere

Answer 2

The javascript version of turning off listener after one invoke is this:

canvas.addEventListener("mousedown",callback,{
        // This will invoke the event once and de-register it afterward
        once: true
});

Answer 3

最简单的解决方案，如果你使用jQuery -用.one()代替.on()这等于触发.off()在http://api.jquery.com/one/

Answer 4

If you're using jQuery, might as well just use Off()

The .off() method removes event handlers that were attached with .on() . Here's the documentation: http://api.jquery.com/off/