Is it possible to get element's numerical index in its parent node without looping? - javascript

Normally I'm doing it this way:
for(i=0;i<elem.parentNode.length;i++) {
if (elem.parentNode[i] == elem) //.... etc.. etc...

function getChildIndex(node) {
return, node);
This seems to work in Opera 11, Firefox 4, Chromium 10. Other browsers untested. It will throw TypeError if node has no parent (add a check for node.parentNode !== undefined if you care about that case).
Of course, Array.prototype.indexOf does still loop, just within the function call. It's impossible to do this without looping.
Note: If you want to obtain the index of a child Element, you can modify the function above by changing childNodes to children.
function getChildElementIndex(node) {
return, node);

Option #1
You can use the Array.from() method to convert an HTMLCollection of elements to an array. From there, you can use the native .indexOf() method in order to get the index:
function getElementIndex (element) {
return Array.from(element.parentNode.children).indexOf(element);
If you want the node index (as oppose to the element's index), then replace the children property with the childNodes property:
function getNodeIndex (element) {
return Array.from(element.parentNode.childNodes).indexOf(element);
Option #2
You can use the .call() method to invoke the array type's native .indexOf() method. This is how the .index() method is implemented in jQuery if you look at the source code.
function getElementIndex(element) {
return [], element);
Likewise, using the childNodes property in place of the children property:
function getNodeIndex (element) {
return [], element);
Option #3
You can also use the spread operator:
function getElementIndex (element) {
return [...element.parentNode.children].indexOf(element);
function getNodeIndex (element) {
return [...element.parentNode.childNodes].indexOf(element);

You could count siblings...
The childNodes list includes text and element nodes-
function whichChild(elem){
var i= 0;
while((elem=elem.previousSibling)!=null) ++i;
return i;

There is no way to get the index of a node within its parent without looping in some manner, be that a for-loop, an Array method like indexOf or forEach, or something else. An index-of operation in the DOM is linear-time, not constant-time.
More generally, if list mutations are possible (and the DOM certainly supports mutation), it's generally impossible to provide an index-of operation that runs in constant time. There are two common implementation tactics: linked lists (usually doubly) and arrays. Finding an index using a linked list requires a walk. Finding an index using an array requires a scan. Some engines will cache indexes to reduce time needed to compute node.childNodes[i], but this won't help you if you're searching for a node. Not asking the question is the best policy.

I think you've got it, but:
make sure that variable "i" is declared with var
use === instead of == in the comparison

If you have a collection input elements with the same name (like <textarea name="text_field[]"…) in your form and you want to get the exact numeric index of the field that triggered an event:
function getElementIdxFromName(elem, parent) {
var elms = parent[];
var i = 0;
if (elms.length === undefined) // there is only one element with this name in the document
return 0;
while((elem!=elms[i])) i++;
return i;
Getting numeric id of an element from a collection of elements with the same class name:
function getElementIdxFromClass(elem, cl) {
var elems = document.getElementsByClassName(cl);
var i = 0;
if (elems.length > 0) {
while((elem!=elems[i])) i++;
return i;
return 0;

Try this:
let element = document.getElementById("your-element-id");
let indexInParent =;


Two blocks in getElementById [duplicate]

doStuff(document.getElementById("myCircle1" "myCircle2" "myCircle3" "myCircle4"));
This doesn't work, so do I need a comma or semi-colon to make this work?
document.getElementById() only supports one name at a time and only returns a single node not an array of nodes. You have several different options:
You could implement your own function that takes multiple ids and returns multiple elements.
You could use document.querySelectorAll() that allows you to specify multiple ids in a CSS selector string .
You could put a common class names on all those nodes and use document.getElementsByClassName() with a single class name.
Examples of each option:
doStuff(document.querySelectorAll("#myCircle1, #myCircle2, #myCircle3, #myCircle4"));
// put a common class on each object
function getElementsById(ids) {
var idList = ids.split(" ");
var results = [], item;
for (var i = 0; i < idList.length; i++) {
item = document.getElementById(idList[i]);
if (item) {
doStuff(getElementsById("myCircle1 myCircle2 myCircle3 myCircle4"));
This will not work, getElementById will query only one element by time.
You can use document.querySelectorAll("#myCircle1, #myCircle2") for querying more then one element.
ES6 or newer
With the new version of the JavaScript, you can also convert the results into an array to easily transverse it.
const elementsList = document.querySelectorAll("#myCircle1, #myCircle2");
const elementsArray = [...elementsList];
// Now you can use cool array prototypes
elementsArray.forEach(element => {
How to query a list of IDs in ES6
Another easy way if you have an array of IDs is to use the language to build your query, example:
const ids = ['myCircle1', 'myCircle2', 'myCircle3'];
const elements = document.querySelectorAll( => `#${id}`).join(', '));
No, it won't work.
document.getElementById() method accepts only one argument.
However, you may always set classes to the elements and use getElementsByClassName() instead. Another option for modern browsers is to use querySelectorAll() method:
document.querySelectorAll("#myCircle1, #myCircle2, #myCircle3, #myCircle4");
I suggest using ES5 array methods:
["myCircle1","myCircle2","myCircle3","myCircle4"] // Array of IDs
.map(document.getElementById, document) // Array of elements
Then doStuff will be called once for each element, and will receive 3 arguments: the element, the index of the element inside the array of elements, and the array of elements.
getElementByID is exactly that - get an element by id.
Maybe you want to give those elements a circle class and getElementsByClassName
document.getElementById() only takes one argument. You can give them a class name and use getElementsByClassName() .
Dunno if something like this works in js, in PHP and Python which i use quite often it is possible.
Maybe just use for loop like:
function doStuff(){
for(i=1; i<=4; i++){
var i = document.getElementById("myCiricle"+i);
Vulgo has the right idea on this thread. I believe his solution is the easiest of the bunch, although his answer could have been a little more in-depth. Here is something that worked for me. I have provided an example.
<h1 id="hello1">Hello World</h1>
<h2 id="hello2">Random</h2>
<button id="click">Click To Hide</button>
document.getElementById('click').addEventListener('click', function(){
function doStuff() {
for(var i=1; i<=2; i++){
var el = document.getElementById("hello" + i); = 'none';
Obviously just change the integers in the for loop to account for however many elements you are targeting, which in this example was 2.
The best way to do it, is to define a function, and pass it a parameter of the ID's name that you want to grab from the DOM, then every time you want to grab an ID and store it inside an array, then you can call the function
<p id="testing">Demo test!</p>
function grabbingId(element){
var storeId = document.getElementById(element);
return storeId;
grabbingId("testing").syle.color = "red";
You can use something like this whit array and for loop.
<p id='fisrt'>??????</p>
<p id='second'>??????</p>
<p id='third'>??????</p>
<p id='forth'>??????</p>
<p id='fifth'>??????</p>
<button id="change" onclick="changeColor()">color red</button>
var ids = ['fisrt','second','third','forth','fifth'];
function changeColor() {
for (var i = 0; i < ids.length; i++) {
For me worked flawles something like this
document.getElementById("myCircle1") ,
document.getElementById("myCircle2") ,
document.getElementById("myCircle3") ,
Use jQuery or similar to get access to the collection of elements in only one sentence. Of course, you need to put something like this in your html's "head" section:
<script type='text/javascript' src='url/to/my/jquery.1.xx.yy.js' ...>
So here is the magic:
.- First of all let's supose that you have some divs with IDs as you wrote, i.e.,
...some html...
<div id='MyCircle1'>some_inner_html_tags</div>
...more html...
<div id='MyCircle2'>more_html_tags_here</div>
<div id='MyCircleN'>more_and_more_tags_again</div>
.- With this 'spell' jQuery will return a collection of objects representing all div elements with IDs containing the entire string "myCircle" anywhere:
This is all! Note that you get rid of details like the numeric suffix, that you can manipulate all the divs in a single sentence, animate them... Voilá!
Prove this in your browser's script console (press F12) right now!
As stated by jfriend00,
document.getElementById() only supports one name at a time and only returns a single node not an array of nodes.
However, here's some example code I created which you can give one or a comma separated list of id's. It will give you one or many elements in an array. If there are any errors, it will return an array with an Error as the only entry.
function safelyGetElementsByIds(ids){
if(typeof ids !== 'string') return new Error('ids must be a comma seperated string of ids or a single id string');
ids = ids.split(",");
let elements = [];
for(let i=0, len = ids.length; i<len; i++){
const currId = ids[i];
const currElement = (document.getElementById(currId) || new Error(currId + ' is not an HTML Element'));
if(currElement instanceof Error) return [currElement];
return elements;
safelyGetElementsByIds('realId1'); //returns [<HTML Element>]
safelyGetElementsByIds('fakeId1'); //returns [Error : fakeId1 is not an HTML Element]
safelyGetElementsByIds('realId1', 'realId2', 'realId3'); //returns [<HTML Element>,<HTML Element>,<HTML Element>]
safelyGetElementsByIds('realId1', 'realId2', 'fakeId3'); //returns [Error : fakeId3 is not an HTML Element]
If, like me, you want to create an or-like construction, where either of the elements is available on the page, you could use querySelector. querySelector tries locating the first id in the list, and if it can't be found continues to the next until it finds an element.
The difference with querySelectorAll is that it only finds a single element, so looping is not necessary.
document.querySelector('#myCircle1, #myCircle2, #myCircle3, #myCircle4');
here is the solution
if (
document.getElementById('73536573').value != '' &&
document.getElementById('1081743273').value != '' &&
document.getElementById('357118391').value != '' &&
document.getElementById('1238321094').value != '' &&
document.getElementById('1118122010').value != ''
) {
You can do it with document.getElementByID Here is how.
function dostuff (var here) {
if(add statment here) {
document.getElementById('First ID'));
document.getElementById('Second ID'));
There you go! xD

Using parent() in a for loop

I am creating a chrome extension that blocks all porn results on all torrent search engine sites.
So I am trying to retrieve the name of the torrents and check them against the array of strings containing blocked (adult/porn) words that I created. If it matches the array word then it should set the display of the parent element to none. But parent() from jQuery doesn't seem to work around this in a for loop. This is the code that I am using.
// 'blockedWords' is the array.
// '$("dl dt")' contains the words that I am checking against strings from
// the array 'blockedWords'.
for (var i = 0; i < $("dl dt").length; i++) {
for (var j = 0; j < blockedWords.length; j++) {
if($("dl dt")[i].innerText.indexOf(blockedWords[j]) > -1){
$(this).parent().style.display= "none"; // 1st Method or
$("dl dt")[i].parent().style.display= "none"; // 2nd Method
// 1st Method shows the error 'Cannot set property 'display' of undefined'
// 2nd Method shows the error '$(...)[i].parent is not a function'
// '$("dl dt")[i].parent().style.display' doesn't work but
// '$("dl dt").parent().style.display' doesn't work either
// '$("dl dt")[i].style.display' works perfectly without parent().
I have also tried 'parents()'.
Any help will be appreciated :).
As a newbie, I am also open to any other suggestions or recommendations.
And I would be really grateful if you could explain your code as well :)
And by the way, can you believe there are more than 500 porn companies out there :o :P :D
Since you have jQuery, you can avoid using nested for-loops using jQuery's filter() and JavaScript reduce(s,v):
// Filter function removes elements that return a false/falsey value like 0
$("dl dt").filter(function() {
// Save current element's innerText so we can use it within the reduce function
var str = $(this).text();
// Return sum of reduce function
return blockedWords.reduce(function(s, v) {
// For each item in blockedWords array, check whether it exists in the string. Add to total number of matches.
return s + !!~str.indexOf(v);
}, 0); // 0 = intial value of reduce function (number of matches)
}).parent().hide(); // Hide elements which pass through the filter function
var blockedWords = [
'shit', 'fuck', 'sex'
$("dl dt").filter(function() {
var str = $(this).text();
return blockedWords.reduce(function(s, v) {
return s + !!~str.indexOf(v);
}, 0);
<script src=""></script>
<dl><dt>this is shit</dt></dl>
<dl><dt>this is okay</dt></dl>
<dl><dt>fuck this</dt></dl>
<dl><dt>no problem</dt></dl>
<dl><dt>sex videos</dt></dl>
EDIT: I apologize for the earlier answer if you saw it, as it was incomplete. I have also added a snippet for demonstration purposes. For further explanation of the reduce algorithm, check this answer out (basically it converts the value of indexOf to either a 0 or 1, because indexOf returns -1 if not found, or another 0-indexed integer of the position if found).
JQuery's parent function returns a JQuery object with the parent element inside of it. If you want to access the element from this object you need to retrieve the element from the object using the bracket notation.
If you were to provide some HTML I would be able to test this and make sure it works, but here is some code that could get you pointed in the right direction to use mostly JQuery instead of relying on for loops with JavaScript.
JQuery Rewrite
$("dl dt").each(function(index, element){
if($.inArray(blockedWords,$(element).text()) > -1) {
$(this).parent().css("display", "block");
$(element).parent().css("display", "block");
The Answer To Your Specific Question
Change this:
$(this).parent().style.display= "none"; // 1st Method or
$("dl dt")[i].parent().style.display= "none"; // 2nd Method
to this:
$(this).parent()[0].style.display= "none"; // 1st Method or
$($("dl dt")[i]).parent()[0].style.display= "none"; // 2nd Method
optionally, you can instead use JQuery's css function like this:
$(this).parent().css("display", "none"); // 1st Method or
$($("dl dt")[i]).parent().css("display","none"); // 2nd Method

Javascript Delete Method?

In this code snippet from AdvancED DOM Scripting:
The call to delete(classes[i]); is this an array or object method? I'm unable to Google an answer.
* remove a class from an element
function removeClassName(element, className) {
if(!(element = $(element))) return false;
var classes = getClassNames(element);
var length = classes.length
//loop through the array in reverse, deleting matching items
// You loop in reverse as you're deleting items from
// the array which will shorten it.
for (var i = length-1; i >= 0; i--) {
if (classes[i] === className) { delete(classes[i]); }
element.className = classes.join(' ');
return (length == classes.length ? false : true);
window['ADS']['removeClassName'] = removeClassName;
The Mozilla Reference Docs says the following regarding the delete operator:
The delete operator deletes an object, an object's property, or an element at a specified index in an array.
For more information, see the following article:
delete will set the value of the specified member (variable/array/object) to undefined
array/object example...
since classes[i] is actually referencing the i index of the array. It will set that specific index position to undefined, reserving the position in the array...
I think you can use simply $('p').removeClass('myClass yourClass') with jquery and put together a function to do so for any element

How to filter elements returned by QuerySelectorAll

I'm working on a javascript library, and I use this function to match elements:
$ = function (a)
var x;
if (typeof a !== "string" || typeof a === "undefined"){ return a;}
//Pick the quickest method for each kind of selector
return document.getElementById(a.split('#')[1]);
else if(a.match(/^([\w\-]+)$/))
x = document.getElementsByTagName(a);
x = document.querySelectorAll(a);
//Return the single object if applicable
return (x.length === 1) ? x[0] : x;
There are occasions where I would want to filter the result of this function, like pick out a div span, or a #id div or some other fairly simple selector.
How can I filter these results? Can I create a document fragment, and use the querySelectorAll method on that fragment, or do I have to resort to manual string manipulation?
I only care about modern browsers and IE8+.
If you want to look at the rest of my library, it's here:
To clarify, I want to be able to do something like $_(selector).children(other_selector) and return the children elements matching that selector.
So here's my potential solution to the simplest selectors:
tag_reg = /^([\w\-]+)$/;
id_reg = /#([\w\-]+$)/;
class_reg = /\.([\w\-]+)$/;
function _sel_filter(filter, curr_sel)
var i,
len = curr_sel.length,
matches = [];
if(typeof filter !== "string")
return filter;
//Filter by tag
if(curr_sell[i].tagName.toLowerCase() == filter.toLowerCase())
else if(filter.match(class_reg))
else if(filter.match(id_reg))
return document.getElementById(filter);
console.log(filter+" is not a valid filter");
return (matches.length === 1) ? matches[0] : matches;
It takes a tag like div, an id, or a class selector, and returns the matching elements with the curr_sel argument.
I don't want to have to resort to a full selector engine, so is there a better way?
I don't think I get the question right. Why would you want to "filter" the result of querySelectorAll() which infact, is some kind of a filter itself. If you query for div span or even better #id div, those results are already filtered, no ?
However, you can apply Array.prototype.filter to the static result of querySelectorAll like follows:
var filter = Array.prototype.filter,
result = document.querySelectorAll('div'),
filtered = result, function( node ) {
return !!node.querySelectorAll('span').length;
That code would first use querySelectorAll() to query for all <div> nodes within the document. Afterwards it'll filter for <div> nodes which contain at least one <span>. That code doesn't make much sense and is just for demonstrative purposes (just in case some SO member wants to create a donk comment)
You can also filter with Element.compareDocumentPosition. I'll also tell if Elements are disconnected, following, preceding, or contained. See MDC .compareDocumentPosition()
Note: NodeList is not a genuine array, that is to say it doesn't have
the array methods like slice, some, map etc. To convert it into an
array, try Array.from(nodeList).
for example:
let highlightedItems = Array.from(userList.querySelectorAll(".highlighted"));
highlightedItems.filter((item) => {
Most concise way in 2019 is with spread syntax ... plus an array literal [...], which work great with iterable objects like the NodeList returned by querySelectorAll:
[...document.querySelectorAll(".myClass")].filter(el=>{/*your code here*/})
Some browsers that support qsa also support a non-standard matchesSelector method, like:
...that will return a boolean representing whether element matched the selector provided. So you could iterate the collection, and apply that method, retaining positive results.
In browsers that don't have a matchesSelector, you'd probably need to build your own selector based method similar to the selector engine you're building.

ID Ends With in pure Javascript

I am working in a Javascript library that brings in jQuery for one thing: an "ends with" selector. It looks like this:
It will find the elements in which the id ends with "foo".
I am looking to do this without jQuery (straight JavaScript). How might you go about this? I'd also like it to be as efficient as reasonably possible.
Use querySelectorAll, not available in all browsers (like IE 5/6/7/8) though. It basically works like jQuery:
You will need to iterate over all elements on the page and then use string functions to test it. The only optimizations I can think of is changing the starting point - i.e. not document.body but some other element where you know your element will be a child of - or you could use document.getElementsByTagName() to get an element list if you know the tag name of the elements.
However, your task would be much easier if you could use some 3rd-party-javascript, e.g. Sizzle (4k minified, the same selector engine jQuery uses).
So, using everything that was said, I put together this code. Assuming my elements are all inputs, then the following code is probably the best I am going to get?
String.prototype.endsWith = function(suffix) {
return this.indexOf(suffix, this.length - suffix.length) !== -1;
function getInputsThatEndWith(text) {
var result = new Array();
var inputs = document.getElementsByTagName("input");
for(var i=0; i < inputs.length; i++) {
return result;
I put it on JsFiddle:
#ThiefMaster touched on how you can do the check, but here's the actual code:
function idEndsWith(str)
if (document.querySelectorAll)
return document.querySelectorAll('[id$="'+str+'"]');
var all,
elements = [],
all = document.getElementsByTagName('*');
len = all.length;
regex = new RegExp(str+'$');
for (i = 0; i < len; i++)
if (regex.test(all[i].id))
return elements;
This can be enhanced in a number of ways. It currently iterates through the entire dom, but would be more efficient if it had a context:
function idEndsWith(str, context)
if (!context)
context = document;
...CODE... //replace all occurrences of "document" with "context"
There is no validation/escaping on the str variable in this function, the assumption is that it'll only receive a string of chars.
Suggested changes to your answer:
RegExp.quote = function(str) {
return str.replace(/([.?*+^$[\]\\(){}-])/g, "\\$1");
}; // from
String.prototype.endsWith = function(suffix) {
return !!this.match(new RegExp(RegExp.quote(suffix) + '$'));
function getInputsThatEndWith(text) {
var results = [],
inputs = document.getElementsByTagName("input"),
numInputs = inputs.length,
for(var i=0; i < numInputs; i++) {
var input = inputs[i];
if( results.push(input);
return results;
Implementing String.endsWith using a regex instead of indexOf() is mostly a matter of preference, but I figured it was worth including for variety. If you aren't concerned about escaping special characters in the suffix, you can remove the RegExp.quote() bit, and just use
new RegExp(suffix + '$').
If you know the type of DOM elements you are targeting,
then get a list of references to them using getElementsByTagName , and then iterate over them.
You can use this optimization to fasten the iterations:
ignore the elements not having id.
target the nearest known parent of elements you want to seek, lets say your element is inside a div with id='myContainer', then you can get a restricted subset using
document.getElementById('myContainer').getElementsByTagName('*') , and then iterate over them.