events.js

function createEvent(type, bubbles, cancelable) {
    var ev
    bubbles = bubbles || true
    cancelable = cancelable || true
    if (document.createEvent) {
        ev = document.createEvent("Event")
        ev.initEvent(type, bubbles, cancelable)               
    } else if (document.createEventObject) {
        ev = document.createEventObject()
    } else {
        ev = {}    
    }
    return ev
}

function dispatchEvent(et, event) {
    var ev
    if (typeof event !== "string") {
        ev = event
    } else if (event) {
        ev = createEvent(event)
    }

    if (et.dispatchEvent) {
        return et.dispatchEvent(ev)
    } else if (et.fireEvent) {
        return et.fireEvent("on" + type, ev)
    } else if (typeof et["on" + type] === "function") {
        return et["on" + type](ev)
    }
    return new Error("Cannot dispatch event")
}

function addEventListener(et, type, callback, capture) {
    if (et.addEventListener) {
        et.addEventListener(type, callback, capture || false)
    } else if (et.attachEvent) {
        et.attachEvent("on" + type, callback)
    } else if (typeof et["on" + type] !== "undefined") {
        et["on" + type] = callback
    }
}

function removeEventListener(et, type, callback, capture) {
    if (et.removeEventListener) {
        et.removeEventListener(type, callback, capture || false)
    } else if (et.detachEvent) {
        et.detachEvent("on" + type, callback)
    } else if (et["on" + type] === callback) {
        et["on" + type] = null
    }
}