Create elements in javascript. Useful to me, not that useful in general.

createEl.js

var createEl = function(type, props, children) {
    var el = document.createElement(type);
    if (props) {
        for (var key in props) {
            if (props.hasOwnProperty(key)) {
                if (key == "css") {
                    if (props[key].length > 0) {
                        el.style.cssText = props[key].join(';') + ";";
                    }
                } else {
                    el.setAttribute(key, props[key]);
                }
            }
        }
    }
    if (children) {
        for (var i = 0;i < children.length;i++) {
            el.appendChild(children[i]);
        }
    }
    return el;
};