Insert based on class

Insert at cursor via javascript, but only within certain class.

HTML

<div class="editor-text" contenteditable="true">Lorem ipsum dolor sit amet, consectetur adipisicing elit. Laboriosam voluptatibus ex ipsum officia numquam odit in id neque perspiciatis natus ducimus quas cum distinctio atque dolores non saepe libero officiis! <b>Try Inserting in the whitespace below</b>
    <br>
    <br>
    <br>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Totam maiores aliquam odio nemo quasi quisquam non nisi voluptas odit reiciendis molestias sit repellendus id eos harum sunt ut recusandae laudantium.</div>
<a href="#" id="insert">Insert Button</a>

CSS

div {
    border:1px solid blue;
    padding:15px;
}

JavaScript

function pasteHtmlAtCaret(html, selector) {
    var sel, range, parent, node = null;

    if (document.selection) {
        node = document.selection.createRange().parentElement();
    } else {
        var selection = window.getSelection();
        if (selection.rangeCount > 0) node = selection.getRangeAt(0).startContainer.parentNode;
    }

    if (node && $(node).closest(selector).length > 0 && window.getSelection) {
        sel = window.getSelection();
        if (sel.getRangeAt && sel.rangeCount) {
            range = sel.getRangeAt(0);
            range.deleteContents();
            var el = document.createElement("div");
            el.innerHTML = html;
            var frag = document.createDocumentFragment(),
                node, lastNode;
            while ((node = el.firstChild)) {
                lastNode = frag.appendChild(node);
            }
            range.insertNode(frag);

            if (lastNode) {
                range = range.cloneRange();
                range.setStartAfter(lastNode);
                range.collapse(true);
                sel.removeAllRanges();
                sel.addRange(range);
            }
        }
    } else if (document.selection && document.selection.type != "Control") {
        document.selection.createRange().pasteHTML(html);
    }
}

$('#insert').click(function () {
    pasteHtmlAtCaret('<b>（´・ω・） </b>', '.editor-text');
});