Develop Reference

Make all other Divs dissapear javascript

I got a Script Which makes me onclick showing all Divs with Specific id
This is the Selector
<a onclick="filterGal('simpleCart_shelfItem item Sonnenbrillen')" href="javascript:void(0);">Sonnenbrillen</a>
this is my Script
function filterGal(foo) {
var toHide = document.getElementsByClassName(foo);
for (i = 0; i < toHide.length; i++) {
toHide[i].style.display = 'block';
}
}
So now my question how can i only show specific div with classname and display none the other div with other classnames?

Try this :
function filterGal(foo) {
var toHide = document.getElementsByTagName('div');
for (i = 0; i < toHide.length; i++) {
toHide[i].style.display = 'none';
}
var toShow = document.getElementsByClassName(foo);
for (i = 0; i < toShow.length; i++) {
toShow[i].style.display = 'block';
}
}
Can be improved by skiping in the first loop div which match your classes.

I just show you add jquery tag so you just need to do this :
function filterGal(foo) {
$( "div:not("+foo+")" ).hide();
}
Exemple : http://jsfiddle.net/ACjeZ/1

This is what I would try:
$("div").Hide();
$("." + foo).Show();

If data attribute above X number add class to element

I need to add Class highpc to each element with the data attribute of procent, which is bigger than 51. I've got a jQuery solution, but I need it in pure JavaScript. Can anyone help me? This is what I got so far:
HTML
<span data-procent="4" class="procent">4%</span>
<span data-procent="59" class="procent">59%</span>
JS
function highpc(){
var procent = this.elem.getAttribute("data-procent");
if (parseInt(procent) > 51) {
procent.className=procent.className+" highpc";
}
}
window.onload = highpc();
http://jsfiddle.net/Zc8vY/1/

You haven't specified what is this.elem, and you haven't loop in your script.
You are also using variable procent for getting the data-attribute from your element. Later, you are trying to use it for linking the element. Try updated code:
function highpc(){
var elements = document.getElementsByClassName('procent');
for(i=0;i<elements.length;i++) {
var procent = elements[i].getAttribute("data-procent");
if (parseInt(procent) > 51) {
elements[i].className=elements[i].className+" highpc";
}
}
}
Updated fiddle http://jsfiddle.net/Zc8vY/4/

This is your fixed function:
function highpc() {
var elements = document.querySelectorAll('.procent');
for (var i = 0; i < elements.length; i++) {
var procent = elements[i].getAttribute("data-procent");
if (parseInt(procent) > 51) {
elements[i].className += " highpc";
}
}
}
window.onload = highpc;
Note the last line: you don't need () after highpc because you want window.onload to be a reference to a function, not a result of execution.
References: querySelectorAll to select elements.
Demo: http://jsfiddle.net/Zc8vY/3/

Using pure javascript and implementing own getElementsByClassName.
function getElementsByClass(className){
var celems = new Array();
var elems = document.getElementsByTagName("*");
for(var i = 0; i < elems.length;i++){
if(elems[i].className.indexOf(className) != -1){
celems.push(elems[i]);
}
}
return celems;
}
function highpc(){
var elems = getElementsByClass("procent");
console.log(elems);
for(var i = 0; i < elems.length; i++){
highpc_ex(elems[i]);
}
}
function highpc_ex(elem){
var procent = elem.getAttribute("data-procent");
if (parseInt(procent) > 51) {
elem.className=elem.className+" highpc";
}
}
window.onload = highpc();

WORKING FIDDLE HERE
function highpc() {
var aSpans = document.getElementsByTagName("span");
for(var i = 0; i < aSpans.length; i++) {
var eSpan = aSpans[i];
var procent = eSpan.getAttribute("data-procent");
if (procent != null && parseInt(procent) > 51) {
eSpan.className += " highpc";
}
}
}
This is a similar variant to what others have already posted. You might find this one to be more performant for larger sets of html.
Ref: Why .getElementsByTagName() is faster than .querySelectorAll()

How to change the style of elements with same class name

Using javascript, I want to change the style of class .s into
.s {
display: block;
}
Why this cannot work:
document.getElementsByClassName('s').style.display='block';

document.getElementsByClassName: returns a set of elements which have all the given class names.
You may have multiple elements with this class name. so you need to provide index like
document.getElementsByClassName('s')[0].style.display='block';
Inorder to apply for style for all elements with same class name:
var ele = document.getElementsByClassName('s');
for (var i = 0; i < ele.length; i++ ) {
ele[i].style.display = "block";
}

As getElementsByClassName returns an array you need to make a for loop over all found elements:
var elements = document.getElementsByClassName('s');
for (var i = 0; i < elements.length; i++) {
elements[i].style.display = "block";
}

var sCls = document.getElementsByClassName('s');
for(var i in sCls) {
sCls[i].style.display='block';
}
this may work!

Access elements in ul list

I have the following list hierarchy:
<ul id="ulid">
<li><a><div class="mydiv">content</div></a></li>
<li><a><div class="mydiv">content</div></a></li>
...
</ul>
I want to add some css rules to the div and this is what i've tried so far:
var myul = document.getElementById("ulid");
var myli = myul.getElementsByTagName("li");
for(var i = 0; i < myli.length; i++) {
//myli[i].parentNode.style.display = "none"; // that works
var links = myli[i].getElementsByTagName("a");
for(var ii = 0; ii < links.length; ii++) {
links[ii].parentNode.style.display = "none"; // doesnt work
}
}
I can hide the li items but cant do the same for a So i cant reach the div. What am i doing wrong here?
EDIT: getElementsByClassName seems not working in greasemonkey scripts as it simply works in Emmanuel N's fiddle.

Your code seems to work. Check out this Fiddle
var myul = document.getElementById("ulid");
var myli = myul.getElementsByTagName("li");
for(var i = 0; i < myli.length; i++)
{
var links = myli[i].getElementsByTagName("a");
for(var ii = 0; ii < links.length; ii++)
{
links[ii].parentNode.style.display = "none";
}
}

Your code actually does work, but I don't think it does what you're intending it to do. The last line: links[ii].parentNode.style.display = "none" will actually hide the parent node of the a tag (i.e. the li) tag, rather than the div. parentNode will go one level UP, not down.
Instead of trying to get myli[i].getElementsByTagName("a") and then working down to the div, why not myli[i].getElementsByTagName("div"), and then simply do:
var myul = document.getElementById("ulid");
var myli = myul.getElementsByTagName("li");
for(var i = 0; i < myli.length; i++) {
//myli[i].parentNode.style.display = "none"; // that works
var links = myli[i].getElementsByTagName("div");
for(var ii = 0; ii < links.length; ii++) {
links[ii].style.display = "none";
}
}
Of course, there are many more efficient ways to do it. You already have classnames on the divs, so
document.getElementsByClassName("mydiv");
would work just as well.
Or, if you use jQuery, you can do the same thing without having to iterate explicitly:
$("div.mydiv").css(etc.); // style this however you want

If you aren't opposed to using jQuery, the following would hide your divs for you.
$(document).ready(function () {
var myDivs = $('div.mydiv');
for(var eachDiv in myDivs) {
$(eachDiv).hide();
}
});

How do I access DOM nodes from an array in javascript?

I am trying to build a drop-down menu that will show a row to the side of it when you hover over one of the cells with the mouse. I'm really new with using the DOM, and javascript as well.
The problem I'm running into is that the array I have created doesn't seem to access what I thought it should. Is it just my syntax, or do I need to approach this differently? Here is my code:
window.onload = function () {
var tableID = "strokerKitMenu";
var table = document.getElementById(tableID);
var tableRows = table.getElementsByTagName("tr");
var tableCell = [];
var counter = 0;
for (i = 0; i < tableRows.length; i++) {
tableCell[i] = new Array();
tableCell[i].push(tableRows[i].getElementsByTagName("td"));
}
for (i = 0; i < tableCell.length; i++) {
tableCell[0, i].style.display = "block"; //This doesn't compile
alert(tableCell[0, i].Text); //This comes back "undefined"
for (j = 1; j < tableCell[i].length; j++) //I haven't even tested this part yet
{
tableCell[i][j].onmouseover = function showCell() {
tableCell[i][j + 1].style.display = "block";
}
tableCell[i][j].onmouseout = function hideCell() {
this.style.display = "none";
}
} //end inner for loop
} //end outer for loop
}

tableCell[0, i].style.display="block"; //This doesn't compile
This syntax is invalid in JavaScript: you have specified two indices for tableCell but I guess you meant tableCell[0][i].style.display="block";
alert(tableCell[0, i].Text); //This comes back "undefined"
Once you fix the first error, you will want to change this to tableCell[0][i].textContent.

tableCell[i].push.apply(tableCell[i], tableRows[i].getElementsByTagName("td"));
You don't want to push the single array in. You want to push all the elements in. Otherwise you would have to access them as tableCell[i][0][j]