parse-tag.js

var classIdSplit = /([\.#]?[a-zA-Z0-9_:-]+)/
var notClassId = /^\.|#/

module.exports = parseTag

function parseTag(tag, props) {
    if (!tag) {
        return "div"
    }

    var noId = !("id" in props)

    var tagParts = tag.split(classIdSplit)
    var tagName = null

    if (notClassId.test(tagParts[1])) {
        tagName = "div"
    }

    var classes, part, type, i
    for (i = 0; i < tagParts.length; i++) {
        part = tagParts[i]

        if (!part) {
            continue
        }

        type = part.charAt(0)

        if (!tagName) {
            tagName = part
        } else if (type === ".") {
            classes = classes || []
            classes.push(part.substring(1, part.length))
        } else if (type === "#" && noId) {
            props.id = part.substring(1, part.length)
        }
    }

    if (classes) {
        if (props.className) {
            classes.push(props.className)
        }

        props.className = classes.join(" ")
    }

    return tagName ? tagName.toLowerCase() : "div"
}