Building HTML with JS (function expression vs comment for code clarity)

Question

I'm currently building some HTML with JS (specifically using the jQuery library). My code is as follows:

goToError: function (error, returnView, returnController, callback) {
    console.log(error);

    this._transitionOutPanel(function () {
        loadError();
    });

    var loadError = function () {
        $("#panel").html("");
        navigation.setHeader("Error");

        (function buildErrorHtml() {
            var ctrlDiv = $('<div></div>', {
                style: "text-align: center;"
            });

            var ctrlP1 = $("<p></p>", {
                html: ("An error occured while loading this view.<br><b>Error code:</b> {0} ({1})").format(error.status, error.statusText)
            }).appendTo(ctrlDiv);

            var ctrlP2 = $("<p></p>").appendTo(ctrlDiv);

            var ctrlBackBtn = $("<button></button>", {
                html: "Back",
                class: "btn btn-danger"
            }).appendTo(ctrlP2);
            ctrlBackBtn.click(function () {
                if (returnView != null && returnController != null) {
                    navigation.go(returnView, returnController);
                } else {
                    navigation.go("Login", "Accounts", null, "Login");
                }
            });

            ctrlDiv.appendTo("#panel");
        })();

        navigation._transitionInPanel(function () {
            if (typeof callback === "function")
                callback.call(this);
        });
    };

    loadError();
}

More specifically, my question is in regards to when it is best to use a comment vs a function expression for code clarity. I currently have a self-invoking function expression named buildErrorHtml() that constructs the HTML and appends it to the relevant element on my page.

Would this be better outside of a function expression (amongst the rest of the code in var loadError = function() { ... }) or should it be as it is, inside an anonymous function? I've been told to only use comments to tell readers 'why' instead of 'what', and I don't feel using a comment is justified with this criteria.

The alternative is using a comment like so:

// Build HTML
var ctrlDiv = $('<div></div>', {
    style: "text-align: center;"
});
...

Which method tells anybody reading my code what it is the code is doing best?

Feedback on anything else is also greatly welcome.