Native JS equivalent to jQuery delegation

Question

What is the native implementation for event delegation on dynamically created dom elements?

I tried looking at the jQuery source but I can't follow the .on method.

Note: Currently I attach the event handlers after the dom elements are created, which seems pretty standard but I like the way jQuery .on handles dynamically created elements events with this syntax $( document ).on( "click", ".selector", handler );.

Answer 1

What happens is basically this:

// $(document).on("click", <selector>, handler)
document.addEventListener("click", function(e) {
    for (var target=e.target; target && target!=this; target=target.parentNode) {
    // loop parent nodes from the target to the delegation node
        if (target.matches(<selector>)) {
            handler.call(target, e);
            break;
        }
    }
}, false);

However, e.currentTarget is document when the handler is called, and e.stop[Immediate]Propagation() will work differently. jQuery abstracts over that (including call order) a lot.

I've used the .matches() method, which is not yet standard but already available under different names in modern browsers. You might use a custom predicate to test elements instead of a selector. And addEventListener is obviously not oldIE-compatible.