What is better, appending new elements via DOM functions, or appending strings with HTML tags?

Some notes:

  • Using innerHTML is faster in IE, but slower in chrome + firefox. Here’s one benchmark showing this with a constantly varying set of <div>s + <p>s; here’s a benchmark showing this for a constant, simple <table>.

  • On the other hand, the DOM methods are the traditional standard — innerHTML is standardized in HTML5 — and allow you to retain references to the newly created elements, so that you can modify them later.

  • Because innerHTML is fast (enough), concise, and easy to use, it’s tempting to lean on it for every situation. But beware that using innerHTML detaches all existing DOM nodes from the document. Here’s an example you can test on this page.

    First, let’s create a function that lets us test whether a node is on the page:

    function contains(parent, descendant) {
        return Boolean(parent.compareDocumentPosition(descendant) & 16);
    }
    

    This will return true if parent contains descendant. Test it like this:

    var p = document.getElementById("portalLink")
    console.log(contains(document, p)); // true
    document.body.innerHTML += "<p>It's clobberin' time!</p>";
    console.log(contains(document, p)); // false
    p = document.getElementById("portalLink")
    console.log(contains(document, p)); // true
    

    This will print:

    true
    false
    true
    

    It may not look like our use of innerHTML should have affected our reference to the portalLink element, but it does. It needs to be retrieved again for proper use.

Leave a Comment