red-letter.js

// wrap first text letter of an element with a span having a specified class
// red letter
// License=WTFPLv2
function redLetterize(element, cls) {
    cls = cls === undefined ? 'first-letter-wrapped' : ('' + cls).replace(/^\s+|\s+$/g, '');
    while (element.firstChild && element.firstChild.tagName) {
        if ((' ' + element.firstChild.className + ' ').indexOf(' ' + cls + ' ') > -1) {
            return;
        }
        element = element.firstChild;
    }
    if (element.firstChild && element.firstChild.nodeType === document.TEXT_NODE) {
        var text = ('' + element.firstChild.data).replace(/^\s+|\s+$/g, ''),
            span, textEl,
            firstCode = text.length &&  text.charCodeAt(0),
            charLen = firstCode >= 0xD800 && firstCode < 0xDC00 ? 2 : 1;
        if (!text.length) {
            return;
        }
        span = document.createElement('span');
        span.appendChild(document.createTextNode(text.substr(0, charLen)));
        span.className = cls;
        element.firstChild.data = text.substr(charLen, text.length);
        element.insertBefore(span, element.firstChild);
    }
}