Develop Reference

getElementById() within $(document).ready() returns null

I am "new" to JavaScript, making my first image- and media-slider for a website.
I have searched for answers in the web and here in SO, but they did not work for me.
My last big change was to divide my script into two parts. One outside of $(document).ready() and one inside. I want the user to be able to call a function via a button in the HTML. To make this possible this function has to be global and can not be located inside the $(document).ready(). Am I right?
Before I divided my script everything was inside the $(document).ready() area and it worked properly. But of cause I could not call the function via a button.
But now the part inside my $(document).ready(), which has to build the slider when the page is loaded, is not waiting for it. All my getElementById()'s are producing the error: "Can't set property 'style' of null." So the slider will not be built.
This is telling me getElementById() returns "null" even if it is inside $(document).ready().
HTML:
<!-- very content -->
<link href="...css" />
<script src="...js" />
<div id="slider"></div>
<!-- more content -->
<div id="changeContent"></div>
<!-- more content -->
</body>
</html>
JavaScript:
// Configuration
var slidersParentId = 'imslider';
var slideShowTitle = '';
var thumbnailWidth = 20;
var slidesWidth = 281.25;
var slidesHeight = 144.5625;
var currentSlideWidth = 500;
var currentSlideHeight = 257;
var nextSlideWidth = 375;
var nextSlideHeight = 192.75;
var prevSlideWidth = nextSlideWidth;
var prevSlideHeight = nextSlideHeight;
var resizeDifference = currentSlideWidth - nextSlideWidth;
var slidesMargin = 20;
var animationDistance = slidesWidth + slidesMargin;
var animationSpeed = 2000;
var intervalSpeed = 7000;
var contentDiv = "descriptif_site_spip";
// Variables from slides.json
var numberOfSlides;
var jsonSlides = {};
var bgImgUrl;
// Cache the DOM
var $slideShow = $('#'+slidersParentId);
var $slideInner;
var $slides;
var $slideNav;
var $navThumb;
var $thumb;
var $hovers;
var $content = document.getElementById(contentDiv);
// Other global Variables
var interval;
var currentSlide = 1;
var nextSlide = currentSlide + 1;
var prevSlide = currentSlide - 1;
var lastSlide = currentSlide;
var lastCurrentDif;
var lastNextSlide = lastSlide + 1;
var lastPrevSlide = lastSlide - 1;
var thumbImgs = [];
var navTo;
var interval;
var i;
// Global Variables for dragging
var dragStartPosition;
var dragStopPosition;
var draggedDistance;
var slidesDragged;
var posSlidesDragged;
var negSlidesDragged;
// IRIS-MEDIA-MODUS ?!
var iris_mode = 1;
//global functions...
//global warming...
$(document).ready(function(){
$.ajax({}
//getting some json...
});
// Building the slideshow windows
if (slideShowTitle !== 0) {
$slideShow.append('<h2 class="slideShowTitle">'+slideShowTitle+'</h2>');
}
$slideShow.append('<div id="outerWindow"><div id="innerWindowPositioner"<div id="innerWindow"></div></div</div>');
$slideInner = $slideShow.find('#innerWindow');
$slideInner.css({'width': numberOfSlides*slidesWidth+numberOfSlides*slidesMargin*currentSlideWidth*3});
// Building the slides & hovers
for (i=1; i<=numberOfSlides; i++) {
var idSlides = "slide_Nr"+i;
alert(idSlides);
var idHover = "hover_Nr"+i;
var j = i-1;
bgImgUrl = "url('" +jsonSlides[j].mediaUrl+ "')";
var title = jsonSlides[j].title;
var artUrl = jsonSlides[j].articleUrl;
var subtitle = jsonSlides[j].subtitle;
var text = jsonSlides[j].text;
var date = jsonSlides[j].date;
$slideInner.append('<div class="slide" id="'+idSlides+'"><div class="hover" id="'+idHover+'"></div></div>');
$('#'+idSlides).css('top', '56.21875px');
document.getElementById(idSlides).style.backgroundImage = bgImgUrl;
$('#'+idHover).append('<div class="hover-title"><h3>'+title+'</h3><span class="hover-subtitle">'+subtitle+'</span></div><span class="hover-date">'+date+'</span><br clear="all" /><p class="hover-text">'+text+'</p>');
}
$slides = $slideInner.find('.slide');
$hovers = $slides.find('.hover');
// Building the thumbnail navigation
$slideShow.append('<div id="slideShowNavigation"><ul id="navigationThumbnails"></ul></div>');
$slideNav = $slideShow.find('#slideShowNavigation');
$navThumb = $slideNav.find('#navigationThumbnails');
for (i=0; i<numberOfSlides; i++) {
thumbImgs[i] = jsonSlides[i].mediaUrl;
// alert(thumbImgs);
}
for (i=1; i<=numberOfSlides; i++) {
j = i-1;
var idThumbs = "thumb_Nr"+i;
bgImgUrl = "url('" +jsonSlides[j].mediaUrl+ "')";
$navThumb.append('<li class="thumb" id="'+idThumbs+'"></li>');
document.getElementById(idThumbs).style.backgroundImage = bgImgUrl;
}
$thumb = $navThumb.find('.thumb');
$( '<li class="year"> > 2000 > </li>' ).insertBefore( "#thumb_Nr62" );
$navThumb.prepend('<li class="year">1980 >> </li>');
$navThumb.append('<li class="year"> 2020&nbsp>></li>');
$navThumb.append('<br clear="both" />');
// ...some
// ...more
// ...functions
});
With this HTML-structure it is not working.
When I put the script-inclusion at the end of my HTML it works correctly and the slider will be built.
So why is my $(document).ready() firing too early?
I also tried $(window).load() but it hat no effect.
Or is there any why to make function inside $(document).ready() globally available without removing it from $(document).ready()?

Probably because your script is running before the rest of the page loads. Try using $(window).ready().
EDIT:
Had wrong function .load() I meant to have .ready()... Whoops!

My last big change was to divide my script into two parts. One outside of $(document).ready() and one inside. I want the user to be able to call a function via a button in the HTML. To make this possible this function has to be global and can not be located inside the $(document).ready().
Actualy, it can:
All global JavaScript objects, functions, and variables automatically become members of the window object.
I suppose you need something like this:
window.addEventListener('DOMContentLoaded', function () {
window.my_magic_function = function (/* my magic params */) {
/* doing my magic */
};
});
<button onclick="my_magic_function(/* my magic params */)">Do magic</button>
window.addEventListener('DOMContentLoaded', ...) equivalent to $(document).ready(...)

Javascript - strikethrough

i try to make text strikethrough with javascript.
I know nothing about Javascript and try to search on the net how to that.
<script language="JavaScript">
function recal(val,sum)
{
if(sum == true)
{
var total = parseInt(document.getElementById("total").innerHTML, 10);
total+=val;
document.getElementById("total").innerHTML=total;
}
else
{
var total = parseInt(document.getElementById("total").innerHTML, 10);
total-=val;
document.getElementById("total").innerHTML=total;
var pnl = document.getElementById("totalEvents");
}
var pnl = document.getElementById("totalEvents");
var pnl2 = document.getElementById("eventCategory");
var pnl3 = document.getElementById("nameID");
**strikethrough starts here**
if (!sum && pnl.firstChild.tagName != "S" && pnl2.firstChild.tagname !="S")
{
pnl.innerHTML = "<S>"+ pnl.innerHTML+"</S>";
pnl2.innerHTML = "<S>"+ pnl2.innerHTML+"</S>";
}
else
{
pnl.innerHTML = pnl.firstChild.innerHTML;
pnl2.innerHTML = pnl2.firstChild.innerHTML;
}
}
</script>
it makes textstrikethrough but something is wrong. Even if i choose second checkbox it affects first checkbox why :(
http://jsfiddle.net/aHH9w/ (my full html page)

You are peforming a pretty convoluted way of achieving this, something that can actually be quite easily done. If you have an HTML element, say with the id 'myelement':
<div id="myelement">Hello world</div>
To create a strikethrough, all you need to do in JS is:
var ele = document.getElementById("myelement");
ele.style.setProperty("text-decoration", "line-through");
If you need to check if there is a strikethrough on an element:
var ele = document.getElementById("myelement");
var isStruck = (ele.style.getProperty("text-decoration") == "line-through");
Although this is not really recommended. Use an internal variable to keep track of state.

javascript height document auto adjust

I got an sidebar which need to adjust to the document size. This works perfectly, its this code:
<script type="text/javascript">
$(document).ready(function(){
$("#sidebar").height( $(document).height() );
});
</script>
But now i got an form in my website which changes with javascript in size when you put in options. So with other words the whole document gets longer when you put in multiple options. But this script doesn't adjust to that so the sidebar just gets cut off when you put in more options.
So with other words is there an possibility to make this script adjust automatically or let the following script rerun the function when it returns:
<script>
treated = new Object();
inputNumber = 1;
function addOne() {
//Create an input type dynamically.
var divElement = document.createElement("div");
var element = document.createElement("input");
inputNumber++;
element.setAttribute("name", "input" +inputNumber);
element.setAttribute("onkeyup", "if (this.value.length > 1 && treated[this.name] != 1){ addOne(); treated[this.name] = '1'; }");
element.setAttribute("id", "productoptiesadd");
var price = document.createElement("input");
price.setAttribute("name", "price" +inputNumber);
price.setAttribute("id", "productoptiesaddprice");
var foo = document.getElementById("japroductopties");
var htag = document.createElement("h7");
htag.innerHTML = "Optie " + inputNumber + ":";
var htags = document.createElement("h7");
htags.innerHTML = " € ";
divElement.appendChild(htag);
divElement.appendChild(element);
divElement.appendChild(htags);
divElement.appendChild(price);
foo.appendChild(divElement);
}
</script>
Hope some1 can help :).

Why not setting #sidebar height property to 100% in your stylesheet ? Is Javascript really necesary ?
Otherwise, just write a function SidebarAutoAdjust() with your first code fragment :
$("#sidebar").height( $(document).height() );
Then all you have to do is calling this function at the end of your addOne() function.

How to remove or reset CSS style using JS?

I want either remove or reset a style applied on a particular DOM node using JS.
node.style.webkitTransitionDuration = '5000ms';
node.style.webkitTransformOrigin = '200px 200px';
node.style.webkitTransform = 'rotateZ(25rad)';
I want to reset/set webkitTransform time and again on a fire of an event
Tried like this
node.style.webkitTransform = 'rotateZ(0rad)';
node.style.webkitTransform = 'rotateZ(25rad)';
But its not working.
P.S. Can not use any framework.

Here's an example that should fit your needs. It toggles when you click on the document. Note: it of course only works in Webkit-based browsers.
animateNode(document.getElementById("test"), "5000ms", "200px 200px", "rotateZ(25rad)");
var toggle = toggleValue();
function animateNode(node, duration, origin, transform)
{
node.style['webkitTransitionDuration'] = duration;
node.style['webkitTransformOrigin'] = origin;
node.style['webkitTransform'] = transform;
}
function toggleValue() {
var num = 1;
return function ()
{
return ++num;
};
}
document.onclick = function()
{
var toggleNum = toggle();
if(toggleNum % 2 === 0)
{
animateNode(document.getElementById("test"), "5000ms", "200px 200px", "rotateZ(0rad)");
}else if(toggleNum % 2 === 1)
{
animateNode(document.getElementById("test"), "5000ms", "200px 200px", "rotateZ(25rad)");
}
}
http://jsfiddle.net/GdGw7/3/

If you are looking to remove the rule from the element then this should work:
node.style.webkitTransform = '';

You say you don't want to use a framework. but if it is OK (according to your comment) to do so:
You can use jQuery:
so you can do in jQuery:
$('selector').css({
webkitTransitionDuration = '5000ms',
webkitTransformOrigin = '200px 200px',
webkitTransform = 'rotateZ(25rad)'
})
you can clear out the style element with:
$('selector').attr('style','');
add class:
$('selector').addClass('newClass');
remove class:
$('selector').removeClass('rClass');

Find an anchor in a Div with javascript

In javascript I have a reference to a div. In that div is an anchor element with a name='foundItem'
How do I get a reference to the anchor with the name foundItem which is in the Div I have the reference of?
There are 'many' foundItem anchors in other divs on the page. I need 'this' DIVs one.

// assuming you're not using jquery or mootools
// assume div is mydiv
var lst = mydiv.getElementsByTagName('a');
var myanchor;
for(var i=0; i<lst.length; ++i) {
if(lst[i].name && lst[i].name == 'foundItem') {
myanchor = lst[i];
break;
}
}
// the mootools method
var myanchor = $(mydiv).getElement('a[name=foundItem]');

You can use the getElementsByTagName method to get the anchor elements in the div, then look for the one with the correct name attribute:
var found = null;
var e = divReference.getElementsByTagName('A');
for (var i=0; i < e.length; i++) {
if (e[i].name && e[i].name == 'foundItem') {
found = e[i];
break;
}
}
If found is not null, you got the element.
If you happen to use the jQuery library, you can let it do the searching:
var found = null;
var e = $(divReference).find('a[name=foundItem]');
if (e.length == 1) found = e.get(0);

Use a JavaScript library like jQuery and save yourself time.
var theAnchor = $('#divId a[name=foundItem]');

Using jquery, it's dead easy:
<script type="text/javascript">
$(function(){
var item = $("#yourDivId a[name=foundItem]")
)};
</script>
Update:
As per the comments, if you have control over what to id/name/class your anchor tag/s, it would be best to apply a class to them:
<div id="firstDiv">
test
</div>
<div id="secondDiv">
test another one
</div>
<!-- and so forth -->
<script type="text/javascript">
$(function(){
var item = $("#firstDiv a.foundItem");
alert(item.html()); // Will result in "test"
var item2 = $("#secondDiv a.foundItem");
alert(item2.html()); // Will show "test another one"
)};
</script>
If you're doing anything with javascript, jQuery saves you tons of time and is worth investing the effort to learn well. Start with http://api.jquery.com/browser/ to get an intro to what's possible.

Not sure if this helps, but wanted a function to handle the load of a page dynamically and scroll to the anchor of choice.
function scrollToAnchor(anchor_val) {
alert("" + anchor_val);
var page = document.getElementById('tables');
var found = null;
var cnt = 0;
var e = document.getElementsByTagName('a');
for (var i = 0; i < e.length; i++) {
if (e[i].name && e[i].name == anchor_val) {
found = e[i];
break;
}
cnt++;
}
if (found) {
var nPos = found.offsetTop;
alert("" + nPos);
page.scrollBy(0, nPos);
} else {
alert('Failed with call of scrollToAnchor()' + cnt);
}
}