Improving Javascript Performance in IE7

Can anyone enlighten me on ways to improve javascript performance, particularly for IE7 as the site I am working on looks fine in Firefox, Safari, and Chrome but has some delay in the Javascript procedures with IE7. Most of the javascript is stuff that people have helped me put together over the years from various places on the net and I've modified it where needed to do what I need.

Thanks
window.faderTimeoutsContent = Array()
function changeOpac(opacity, id) {
    var object = document.getElementById(id).style
    object.opacity = (opacity / 100)
    object.MozOpacity = (opacity / 100)
    object.KhtmlOpacity = (opacity / 100)
    object.filter = "alpha(opacity=" + opacity + ")"
}
function hide(id) {
    eval(document.getElementById(id).style.opacity = 0)
    document.getElementById(id).style.MozOpacity = 0
    document.getElementById(id).style.KhtmlOpacity = 0
    document.getElementById(id).style.filter = "alpha(opacity=" + 0 + ")"
    document.getElementById(id).setAttribute("class", "HideDiv");
    document.getElementById(id).setAttribute("className", "HideDiv");
}
function showcontent(id, millisec) {
    for (i in window.faderTimeoutsContent) {
        if (window.faderTimeoutsContent[i]) { clearTimeout(window.faderTimeoutsContent[i]); }
    }
    if (document.getElementById(id).style.opacity == 100) {
        opacity(id, 100, 0, millisec)
    } else {
        document.getElementById(id).setAttribute("class", "ShowDiv");
        document.getElementById(id).setAttribute("className", "ShowDiv");
        opacity(id, 0, 100, millisec)
    }
    function opacity(id, opacStart, opacEnd, millisec) {
        var speed = Math.round(millisec / 100)
        var timer = 0
        if (opacStart > opacEnd) {
            for (i = opacStart; i >= opacEnd; i--) {
                window.faderTimeoutsContent.push(setTimeout("changeOpac(" + i + ",'" + id + "');;", (timer * speed)))
                timer++
            }
        } else if (opacStart < opacEnd) {
            for (i = opacStart; i <= opacEnd; i++) {
                window.faderTimeoutsContent.push(setTimeout("changeOpac(" + i + ",'" + id + "');;", (timer * speed)))
                timer++
            }
        }
    }
}
function opacity(id, opacStart, opacEnd, millisec) {
    var speed = Math.round(millisec / 100)
    var timer = 0
    if (opacStart > opacEnd) {
        for (i = opacStart; i >= opacEnd; i--) {
            window.faderTimeouts.push(setTimeout("changeOpac(" + i + ",'" + id + "');;", (timer * speed)))
            timer++
        }
    } else if (opacStart < opacEnd) {
        for (i = opacStart; i <= opacEnd; i++) {
            window.faderTimeouts.push(setTimeout("changeOpac(" + i + ",'" + id + "');;", (timer * speed)))
            timer++
        }
    }
}
// JavaScript Document
var timerlen = 7;
var downtimerlen = 10;
var slideAniLen = 500;
var downslideAniLen = 500;
 
var timerID = new Array();
var downtimerID = new Array();
var startTime = new Array();
var downstartTime = new Array();
var obj = new Array();
var downobj = new Array();
var endWidth = new Array();
var downendWidth = new Array();
var moving = new Array();
var downmoving = new Array();
var dir = new Array();
var downdir = new Array();
 
function slideopen(objname) {
    if (moving[objname])
        return;
 
    if (document.getElementById(objname).style.display != "none")
        return; // cannot slide down something that is already visible
 
    moving[objname] = true;
    dir[objname] = "down";
    startslide(objname);
}
 
function slideclosed(objname) {
    if (moving[objname])
        return;
 
    if (document.getElementById(objname).style.display == "none")
        return; // cannot slide up something that is already hidden
 
    moving[objname] = true;
    dir[objname] = "up";
    startslide(objname);
}
 
function slidedown(objname) {
    if (downmoving[objname])
        return;
 
    if (document.getElementById(objname).style.display != "none")
        return; // cannot slide down something that is already visible
 
    downmoving[objname] = true;
    downdir[objname] = "down";
    startslidedown(objname);
}
 
function startslide(objname) {
    obj[objname] = document.getElementById(objname);
 
    endWidth[objname] = parseInt(obj[objname].style.width);
    startTime[objname] = (new Date()).getTime();
 
    if (dir[objname] == "down") {
        obj[objname].style.width = "1px";
    }
 
    if (dir[objname] == "up") {
        obj[objname].style.width = "514px";
    }
 
    obj[objname].style.display = "block";
 
    timerID[objname] = setInterval('slidetick(\'' + objname + '\');', timerlen);
}
 
function startslidedown(objname) {
    downobj[objname] = document.getElementById(objname);
 
    downendWidth[objname] = parseInt(downobj[objname].style.width);
    downstartTime[objname] = (new Date()).getTime();
 
    if (downdir[objname] == "down") {
        downobj[objname].style.height = "1px";
    }
 
    downobj[objname].style.display = "block";
 
    downtimerID[objname] = setInterval('slidetickdown(\'' + objname + '\');', downtimerlen);
}
 
function slidetickdown(objname) {
    var elapsed = (new Date()).getTime() - downstartTime[objname];
 
    if (elapsed > downslideAniLen)
        downendSlide(objname)
    else {
        var d = Math.round(elapsed / downslideAniLen * downendWidth[objname]);
        if (downdir[objname] == "up")
            d = downendWidth[objname] - d;
 
        downobj[objname].style.height = d + "px";
    }
    return;
}
 
function slidetick(objname) {
    var elapsed = (new Date()).getTime() - startTime[objname];
 
    if (elapsed > slideAniLen)
        endSlide(objname)
    else {
        var d = Math.round(elapsed / slideAniLen * endWidth[objname]);
        if (dir[objname] == "up")
            d = endWidth[objname] - d;
 
        obj[objname].style.width = d + "px";
    }
 
    return;
}
 
function endSlide(objname) {
    clearInterval(timerID[objname]);
 
    if (dir[objname] == "up")
        obj[objname].style.display = "none";
 
    obj[objname].style.width = endWidth[objname] + "px";
 
    delete (moving[objname]);
    delete (timerID[objname]);
    delete (startTime[objname]);
    delete (endWidth[objname]);
    delete (obj[objname]);
    delete (dir[objname]);
 
    return;
}
 
function downendSlide(objname) {
    clearInterval(downtimerID[objname]);
 
    if (downdir[objname] == "up")
        downobj[objname].style.display = "none";
 
    downobj[objname].style.height = downendWidth[objname] + "px";
 
    delete (downmoving[objname]);
    delete (downtimerID[objname]);
    delete (downstartTime[objname]);
    delete (downendWidth[objname]);
    delete (downobj[objname]);
    delete (downdir[objname]);
 
    return;
}
var x = 0; //Starting Location - left
var y = 0; //Starting Location - top
var dest_x = 340;  //Ending Location - left
var interval = 10; //Move 10px every initialization
 
function moveImage() {
    //Keep on moving the image till the target is achieved
    if (x < dest_x) x = x + interval;
    //Move the image to the new location
    document.getElementById("menu_options").style.left = x + 'px';
 
    if (x + interval < dest_x) {
        //Keep on calling this function every 100 microsecond 
        //	till the target location is reached
        window.setTimeout('moveImage()', 10);
    }
}
 
var abx = -200; //Starting Location - left
var abdest_x = 330;  //Ending Location - left
var abinterval = 10; //Move 10px every initialization
 
function moveaboutImage() {
    //Keep on moving the image till the target is achieved
    if (abx < abdest_x) abx = abx + abinterval;
    //Move the image to the new location
    document.getElementById("menu_options").style.left = abx + 'px';
 
    if (abx + abinterval < abdest_x) {
        //Keep on calling this function every 100 microsecond 
        //	till the target location is reached
        window.setTimeout('moveaboutImage()', 10);
    }
}
/*
 
Correctly handle PNG transparency in Win IE 5.5 & 6.
http://homepage.ntlworld.com/bobosola. Updated 18-Jan-2006.
 
Use in <HEAD> with DEFER keyword wrapped in conditional comments:
<!--[if lt IE 7]>
<script defer type="text/javascript" src="pngfix.js"></script>
<![endif]-->
 
*/
 
var arVersion = navigator.appVersion.split("MSIE")
var version = parseFloat(arVersion[1])
 
if ((version >= 5.5) && (document.body.filters)) {
    for (var i = 0; i < document.images.length; i++) {
        var img = document.images[i]
        var imgName = img.src.toUpperCase()
        if (imgName.substring(imgName.length - 3, imgName.length) == "PNG") {
            var imgID = (img.id) ? "id='" + img.id + "' " : ""
            var imgClass = (img.className) ? "class='" + img.className + "' " : ""
            var imgTitle = (img.title) ? "title='" + img.title + "' " : "title='" + img.alt + "' "
            var imgStyle = "display:inline-block;" + img.style.cssText
            if (img.align == "left") imgStyle = "float:left;" + imgStyle
            if (img.align == "right") imgStyle = "float:right;" + imgStyle
            if (img.parentElement.href) imgStyle = "cursor:hand;" + imgStyle
            var strNewHTML = "<span " + imgID + imgClass + imgTitle
         + " style=\"" + "width:" + img.width + "px; height:" + img.height + "px;" + imgStyle + ";"
         + "filter:progid:DXImageTransform.Microsoft.AlphaImageLoader"
         + "(src=\'" + img.src + "\', sizingMethod='scale');\"></span>"
            img.outerHTML = strNewHTML
            i = i - 1
        }
    }
}
function MM_findObj(n, d) { //v4.01
    var p, i, x; if (!d) d = document; if ((p = n.indexOf("?")) > 0 && parent.frames.length) {
        d = parent.frames[n.substring(p + 1)].document; n = n.substring(0, p);
    }
    if (!(x = d[n]) && d.all) x = d.all[n]; for (i = 0; !x && i < d.forms.length; i++) x = d.forms[i][n];
    for (i = 0; !x && d.layers && i < d.layers.length; i++) x = MM_findObj(n, d.layers[i].document);
    if (!x && d.getElementById) x = d.getElementById(n); return x;
}
function MM_swapImage() { //v3.0
    var i, j = 0, x, a = MM_swapImage.arguments; document.MM_sr = new Array; for (i = 0; i < (a.length - 2); i += 3)
        if ((x = MM_findObj(a[i])) != null) { document.MM_sr[j++] = x; if (!x.oSrc) x.oSrc = x.src; x.src = a[i + 2]; }
}
function MM_swapImgRestore() { //v3.0
    var i, x, a = document.MM_sr; for (i = 0; a && i < a.length && (x = a[i]) && x.oSrc; i++) x.src = x.oSrc;
}
 
function MM_preloadImages() { //v3.0
    var d = document; if (d.images) {
        if (!d.MM_p) d.MM_p = new Array();
        var i, j = d.MM_p.length, a = MM_preloadImages.arguments; for (i = 0; i < a.length; i++)
            if (a[i].indexOf("#") != 0) { d.MM_p[j] = new Image; d.MM_p[j++].src = a[i]; }
    }
}

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Curtis_ShirleyAsked:
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Michel PlungjanConnect With a Mentor IT ExpertCommented:
Not to mention

    eval(document.getElementById(id).style.opacity = 0)
    document.getElementById(id).style.MozOpacity = 0
    document.getElementById(id).style.KhtmlOpacity = 0
    document.getElementById(id).style.filter = "alpha(opacity=" + 0 + ")"
    document.getElementById(id).setAttribute("class", "HideDiv");
    document.getElementById(id).setAttribute("className", "HideDiv");

can be written
  var obj =  document.getElementById(id); // get it ONCE
  var theStyle = obj.style;
  theStyle.opacity = theStyle.MozOpacity = theStyle.KhtmlOpacity = 0;
  if (theStyle.filter) theStyle.filter = "alpha(opacity=0)"
  obj.className="HideDiv";

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0
 
Michel PlungjanIT ExpertCommented:
Use flash.

You have too much going on on that page
0
 
Curtis_ShirleyAuthor Commented:
Ok, let me scrap everything I've done then and get right on that... thanks but I'd prefer not to have to learn another programming language just to make sites work nicely in IE.
0
 
Michel PlungjanConnect With a Mentor IT ExpertCommented:
Seriously. I count sliding, opacity change filters on all images png fixing and so on.

I would be scared to open that page.

Perhaps use one or two things but 4 or 5 and some are similar using different code?

At least make the opacity change use the IE built-in fading
0
 
David S.Connect With a Mentor Commented:
For one thing, AlphaImageLoader, is for IE5.5 and IE6 only. IE7 natively supports the alpha channel on PNG-24s and thus doesn't need it.

Another thing I would change is

    document.getElementById(id).setAttribute("class", "HideDiv");
    document.getElementById(id).setAttribute("className", "HideDiv");

to just:

    document.getElementById(id).setAttribute("class", "HideDiv");
    document.getElementById(id).className = "HideDiv";

or even better would be to use an addClass function, so you support elements with multiple classes.
0
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