Question

When registering an event via addEventListener on an element, then delete that element without removing the event, and doing so repeatedly, would memory be “leaked”?

Answer 1

It shouldn’t leak. The one browser that’s infamous for leaking like hell when an event handler causes a host-object<>JS-object loop is IE (up to version 7), and IE (up to version 8) doesn’t support addEventListener.

Leave this running and see how the browser’s memory usage is affected in the long term, if you want to test it in a particular browser.

<div id="x"></div>
<script type="text/javascript">
    function replace() {
        var x= document.getElementById('x');
        if (x.firstChild!==null)
            x.removeChild(x.firstChild);
        var el= document.createElement('p');
        el.addEventListener('click', click, false);
        x.appendChild(el);
    }
    function click() {
        alert('click');
    };
    setInterval(replace, 1);
</script>

(To test it with a reference loop present, move the function click definition up into the replace body.)