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CSS selector for all elements starting with a prefix

I have several polymer elements.
<ps-el-one/>
<ps-el-two/>
<ps-el-three/>
<ps-el-four/>
I want to be able to query all of the elements which begin with "ps-" with either a CSS selector or javaScript.
I whipped up the following solution, but I am wondering if there is anything more efficient?
var allElementsOnPage = document.querySelectorAll('*');
var res = [];
for (var index in allElementsOnPage) {
var el = allElementsOnPage[index];
if (el && el.tagName && el.tagName.substr(0, 3) == 'PS-') {
res.push(el);
}
}
This solution seems very inefficient.

I'm not aware of any element selector, but it is possible with CSS3 attribute and class substring-matching selectors (which are supported in IE7+):
[class^="tocolor-"], [attr*=" tocolor-"] {
color:red
}
Not sure if this is what you want, but probably gives you another way of achieving the same.

Check this here
<input name="man-news">
<input name="milkman">
<input name="letterman2">
<input name="newmilk">
<script>
$( "input[name*='man']" ).val( "has man in it!" );
</script>

You can use something like this instead of querySelectorAll
function myFunction() {
var x = document.getElementsByTagName("*");
var res = [];
for(var i = 0; i < x.length; i++) {
if(x[i].tagName.indexOf('PS-') == 0) {
res.push(x[i]);
}
}
}

Just give a class to all the elements common in nature. and do:
HTML
<ps-el-one class="ps"/>
<ps-el-two class="ps"/>
<ps-el-three class="ps"/>
<ps-el-four class="ps"/>
CSS
// for all elements together
.ps { /* css for all elements together */ }
// for individual elements
.ps:nth-of-type(1) { /* css for 1st ele */ }
.ps:nth-of-type(2) { /* css for 2nd ele */ }
.ps:nth-of-type(3) { /* css for 3rd ele */ }
.ps:nth-of-type(4) { /* css for 4th ele */ }
JS
// for all elements together
var ps = document.querySelectorAll('.ps');
// for individual elements
var ps1 = document.querySelectorAll('.ps')[0];
var ps2 = document.querySelectorAll('.ps')[1];
var ps3 = document.querySelectorAll('.ps')[2];
var ps4 = document.querySelectorAll('.ps')[3];

find DOM elements that have no attributes?

I'm trying to find all span tags that have no attributes -- no class, no styling, no nothing. I've been doing this:
function hasAttributes(span) {
if (span.outerHTML.slice(0,6) === '<span>') return true;
return false;
}
Is there a better (faster) way to check if a particular element qualifies?

You can use querySelectorAll() to select all spans and then use for loop to filter spans by attributes property. If span doesn't have any attributes it will return empty array.
var spans = document.querySelectorAll('span');
for (var i = 0; i < spans.length; i++) {
if (spans[i].attributes.length == 0) spans[i].style.color = 'blue';
}
<span>one</span>
<span class="two">Two</span>

Check attributes property of element for length
function hasAttributes(span){
return span.attributes.length;
}

Access dynamic generated div id

I have some div ids that are generated dynamicly via php
<div id='a<?php echo $gid?>>
How can I access them in JavaScript? All these divs start with "A" followed by a number.
Is there some kind of search function
getElementById(a*)?
Thanks for any help

No generic JavaScript function for this (at least not something cross browser), but you can use the .getElementsByTagName and iterate the result:
var arrDivs = document.getElementsByTagName("div");
for (var i = 0; i < arrDivs.length; i++) {
var oDiv = arrDivs[i];
if (oDiv.id && oDiv.id.substr(0, 1) == "a") {
//found a matching div!
}
}
This is the most low level you can get so you won't have to worry about old browsers, new browsers or future browsers.
To wrap this into a neater function, you can have:
function GetElementsStartingWith(tagName, subString) {
var elements = document.getElementsByTagName(tagName);
var result = [];
for (var i = 0; i < elements.length; i++) {
var element = elements[i];
if (element.id && element.id.substr(0, subString.length) == subString) {
result.push(element);
}
}
return result;
}
The usage example would be:
window.onload = function() {
var arrDivs = GetElementsStartingWith("div", "a");
for (var i = 0; i < arrDivs.length; i++) {
arrDivs[i].style.backgroundColor = "red";
}
};
Live test case.
In case you choose to use jQuery at some point (not worth for this thing alone) all the above code turns to single line:
$(document).ready(function() {
$('div[id^="a"]').css("background-color", "blue");
});
Updated fiddle, with jQuery.

No, you need a fixed id value for getElementById to work. However, there are other ways to search the DOM for elements (e.g. by CSS classes).

You can use querySelectorAll to get all divs that have an ID starting with a. Then check each one to see if it contains a number.
var aDivs = document.querySelectorAll('div[id^="a"]');
for(var index = 0, len = aDivs.length; index < len; index++){
var aDiv = aDivs[index];
if(aDiv.id.match(/a\d+/)){
// aDiv is a matching div
}
}​
DEMO: http://jsfiddle.net/NTICompass/VaTMe/2/

Well, I question myself why you would need to select/get an element, that has a random ID. I would assume, you want to do something with every div that has a random ID (like arranging or resizing them).
In that case -> give your elements a class like "myGeneratedDivs" with the random ID (if you need it for something).
And then select all with javascript
var filteredResults=document.querySelectorAll(".myGeneratedDivs").filter(function(elem){
....
return true;
});
or use jQuery/Zepto/YourWeaponOfChoice
var filteredResults=$(".myGeneratedDivs").filter(function(index){
var elem=this;
....
return true;
});

If you plan to use jQuery, you can use following jQuery selectors
div[id^="a"]
or
$('div[id^="id"]').each(function(){
// your stuff here
});

You will have to target the parent div and when someone click on child div inside a parent div then you can catch the child div.
<div id="target">
<div id="tag1" >tag1</div>
<div id="tag1" >tag2</div>
<div id="tag1" >tag3</div>
</div>
$("#target").on("click", "div", function() {
var showid = $(this).attr('id');
alert(showid)
});

getElementById() will return the exact element specified. There are many javascript frameworks including jQuery that allow much more powerful selection capabilities. eg:
Select an element by id: $("#theId")
Select a group of elements by class: $(".class")
Select subelements: $("ul a.action")
For your specific problem you could easily construct the appropriate selector.

effect all nodes with a shared class

I have a page with div's that each have multiple classes.
<div class='publication parent20'></div>
<div class='publication parent12 parent42 parent91'></div>
<div class='publication parent20'></div>
<div class='publication parent32 parent23'></div>
I need a function that takes a class passed to it as a variable, sets they style of all divs with publication class to none and then sets tags with the specified class.
function swap_pub(pub){
document.getElementById("publication").style.display = "none";
//set style.display = "block" to all elements with class = pub
}
any thoughts on how I would do this.

Use getElementsByClassName()MDN
var pubs = document.getElementsByClassName('publication'); // a NodeList
for (var i = 0; i < pubs.length; i++) {
pubs[i].style.display = 'block';
}
This is how it looks using jQuery:
$('.publication').show(); // concise

There is also querySelectorAll which is slightly more widely supported than getElementsByClassName.
function setDisplay(className, display) {
var items = document.querySelectorAll('.' + className);
var i = items.length;
while (i--) {
items[i].style.display = display;
}
}

How to get all elements inside "div" that starts with a known text

I have a div element in an HTML document.
I would like to extract all elements inside this div with id attributes starting with a known string (e.g. "q17_").
How can I achieve this using JavaScript ?
If needed, for simplicity, I can assume that all elements inside the div are of type input or select.

var matches = [];
var searchEles = document.getElementById("myDiv").children;
for(var i = 0; i < searchEles.length; i++) {
if(searchEles[i].tagName == 'SELECT' || searchEles.tagName == 'INPUT') {
if(searchEles[i].id.indexOf('q1_') == 0) {
matches.push(searchEles[i]);
}
}
}
Once again, I strongly suggest jQuery for such tasks:
$("#myDiv :input").hide(); // :input matches all input elements, including selects

Option 1: Likely fastest (but not supported by some browsers if used on Document or SVGElement) :
var elements = document.getElementById('parentContainer').children;
Option 2: Likely slowest :
var elements = document.getElementById('parentContainer').getElementsByTagName('*');
Option 3: Requires change to code (wrap a form instead of a div around it) :
// Since what you're doing looks like it should be in a form...
var elements = document.forms['parentContainer'].elements;
var matches = [];
for (var i = 0; i < elements.length; i++)
if (elements[i].value.indexOf('q17_') == 0)
matches.push(elements[i]);

With modern browsers, this is easy without jQuery:
document.getElementById('yourParentDiv').querySelectorAll('[id^="q17_"]');
The querySelectorAll takes a selector (as per CSS selectors) and uses it to search children of the 'yourParentDiv' element recursively. The selector uses ^= which means "starts with".
Note that all browsers released since June 2009 support this.

Presuming every new branch in your tree is a div, I have implemented this solution with 2 functions:
function fillArray(vector1,vector2){
for (var i = 0; i < vector1.length; i++){
if (vector1[i].id.indexOf('q17_') == 0)
vector2.push(vector1[i]);
if(vector1[i].tagName == 'DIV')
fillArray (document.getElementById(vector1[i].id).children,vector2);
}
}
function selectAllElementsInsideDiv(divId){
var matches = new Array();
var searchEles = document.getElementById(divId).children;
fillArray(searchEles,matches);
return matches;
}
Now presuming your div's id is 'myDiv', all you have to do is create an array element and set its value to the function's return:
var ElementsInsideMyDiv = new Array();
ElementsInsideMyDiv = selectAllElementsInsideDiv('myDiv')
I have tested it and it worked for me. I hope it helps you.

var $list = $('#divname input[id^="q17_"]'); // get all input controls with id q17_
// once you have $list you can do whatever you want
var ControlCnt = $list.length;
// Now loop through list of controls
$list.each( function() {
var id = $(this).prop("id"); // get id
var cbx = '';
if ($(this).is(':checkbox') || $(this).is(':radio')) {
// Need to see if this control is checked
}
else {
// Nope, not a checked control - so do something else
}
});

i have tested a sample and i would like to share this sample and i am sure it's quite help full.
I have done all thing in body, first creating an structure there on click of button you will call a
function selectallelement(); on mouse click which will pass the id of that div about which you want to know the childrens.
I have given alerts here on different level so u can test where r u now in the coding .
<body>
<h1>javascript to count the number of children of given child</h1>
<div id="count">
<span>a</span>
<span>s</span>
<span>d</span>
<span>ff</span>
<div>fsds</div>
<p>fffff</p>
</div>
<button type="button" onclick="selectallelement('count')">click</button>
<p>total element no.</p>
<p id="sho">here</p>
<script>
function selectallelement(divid)
{
alert(divid);
var ele = document.getElementById(divid).children;
var match = new Array();
var i = fillArray(ele,match);
alert(i);
document.getElementById('sho').innerHTML = i;
}
function fillArray(e1,a1)
{
alert("we are here");
for(var i =0;i<e1.length;i++)
{
if(e1[i].id.indexOf('count') == 0)
a1.push(e1[i]);
}
return i;
}
</script>
</body>
USE THIS I AM SURE U WILL GET YOUR ANSWER ...THANKS