jQuery .addClass function not adding class - javascript

I'm attempting to add a class for highlighting certain elements on my web page. I'm using the jQuery("selector").addClass("class") function to do that. However, it does not work.
function toggleHighlight(selector, on) {
if (on) {
$(selector).addClass("highlighted");
} else {
$(selector).removeClass("highlighted");
}
}
When the on argument is true and the selector argument is a valid selector, it enters the if clause and exits. Unfortunately the classes of the elements the selector refers to, remain unchanged. I seem to missing something fairly fundamental. Help would be appreciated.
EDIT:
I left out the console.log($(selector)); and console.log($(".highlighted")); statements earlier, for clarity. The first returns the right elements, the second, none (called after .addClass()). The elements themselves are <path> elements created by leaflet for a map (from GeoJSON). As such, the HTML is rather hard to reproduce.
I have called the function form a button on the page: <input type="button" id="toggle-0702" class="btn btn-default" onClick="toggleHighlight('.node-0112', true)" value="turn on" \> as well as directly from the JS console. Same results.
EDIT 2:
Apparently this is an issue with either <path> elements, or (more likely) leaflet. To demonstrate this: http://jsfiddle.net/mrz40jgw/. Notice the shy class on the second circle.

We don't have enough information to say exactly what's going on, but unless you've interferred with jQuery, we can rule out that addClass is broken. Thus, one of the following is likely true:
toggleHighlight is not being called when you think it is. Use console.log to debug this.
$(selector) is not yielding what you think it is. Use console.log to debug this.
Or perhaps most likely:
Adding the class highlight does not affect the targeted elements in the manner you think it ought to, perhaps due to a selector of greater specificity. Debug this by manually setting the class and verify how that affects the visual properties of the element.
Note that jQuery already has a toggle for classes, so your code can be simplified to:
function toggleHighlight(selector, on) {
$(selector).toggleClass("highlighted", on);
}

It would appear that the problem lies with jQuery's inability to change classes on SVG elements: jQuery SVG, why can't I addClass?
For the record, here's my solution in light of the new information:
function toggleHighlight(selector, on) {
var oldClasses = [];
var newClasses = "";
var elements = $(selector)
for (var i = 0; i < elements.length; i++) {
oldClasses = $(elements[i]).attr("class").split(" ");
newClasses = "";
for (var j in oldClasses) {
if (oldClasses[j] != "highlighted") {
newClasses += " " + oldClasses[j];
}}
if (on) {
newClasses += " highlighted";
}
$(elements[i]).attr("class", newClasses.trim());
}}

Related

Safely / completely remove element from DOM [duplicate]

When removing an element with standard JavaScript, you must go to its parent first:
var element = document.getElementById("element-id");
element.parentNode.removeChild(element);
Having to go to the parent node first seems a bit odd to me, is there a reason JavaScript works like this?
I know that augmenting native DOM functions isn't always the best or most popular solution, but this works fine for modern browsers.
Element.prototype.remove = function() {
this.parentElement.removeChild(this);
}
NodeList.prototype.remove = HTMLCollection.prototype.remove = function() {
for(var i = this.length - 1; i >= 0; i--) {
if(this[i] && this[i].parentElement) {
this[i].parentElement.removeChild(this[i]);
}
}
}
And then you can remove elements like this
document.getElementById("my-element").remove();
or
document.getElementsByClassName("my-elements").remove();
Note: this solution doesn't work for IE 7 and below. For more info about extending the DOM read this article.
EDIT: Reviewing my answer in 2019, node.remove() has come to the rescue and can be used as follows (without the polyfill above):
document.getElementById("my-element").remove();
or
[...document.getElementsByClassName("my-elements")].map(n => n && n.remove());
These functions are available in all modern browsers (not IE). Read more on MDN.
Crossbrowser and IE >= 11:
document.getElementById("element-id").outerHTML = "";
You could make a remove function so that you wouldn't have to think about it every time:
function removeElement(id) {
var elem = document.getElementById(id);
return elem.parentNode.removeChild(elem);
}
Update 2011
This was added to the DOM spec back in 2011, so you can just use:
element.remove()
The DOM is organized in a tree of nodes, where each node has a value, along with a list of references to its child nodes. So element.parentNode.removeChild(element) mimics exactly what is happening internally: First you go the parent node, then remove the reference to the child node.
As of DOM4, a helper function is provided to do the same thing: element.remove(). This works in 96% of browsers (as of 2020), but not IE 11.
If you need to support older browsers, you can:
Remove elements via the parent node
Modify the native DOM functions, as in Johan Dettmar's answer, or
Use a DOM4 polyfill.
It's what the DOM supports. Search that page for "remove" or "delete" and removeChild is the only one that removes a node.
For removing one element:
var elem = document.getElementById("yourid");
elem.parentElement.removeChild(elem);
For removing all the elements with for example a certain class name:
var list = document.getElementsByClassName("yourclassname");
for(var i = list.length - 1; 0 <= i; i--)
if(list[i] && list[i].parentElement)
list[i].parentElement.removeChild(list[i]);
you can just use element.remove()
You can directly remove that element by using remove() method of DOM.
here's an example:
let subsWrapper = document.getElementById("element_id");
subsWrapper.remove();
//OR directly.
document.getElementById("element_id").remove();
The ChildNode.remove() method removes the object from the tree it belongs to.
https://developer.mozilla.org/en-US/docs/Web/API/ChildNode/remove
Here is a fiddle that shows how you can call document.getElementById('my-id').remove()
https://jsfiddle.net/52kp584L/
**
There is no need to extend NodeList. It has been implemented already.
**
According to DOM level 4 specs, which is the current version in development, there are some new handy mutation methods available: append(), prepend(), before(), after(), replace(), and remove().
https://catalin.red/removing-an-element-with-plain-javascript-remove-method/
You can simply use
document.getElementById("elementID").outerHTML="";
It works in all browsers, even on Internet Explorer.
Having to go to the parent node first seems a bit odd to me, is there a reason JavaScript works like this?
The function name is removeChild(), and how is it possible to remove the child when there's no parent? :)
On the other hand, you do not always have to call it as you have shown. element.parentNode is only a helper to get the parent node of the given node. If you already know the parent node, you can just use it like this:
Ex:
// Removing a specified element when knowing its parent node
var d = document.getElementById("top");
var d_nested = document.getElementById("nested");
var throwawayNode = d.removeChild(d_nested);
https://developer.mozilla.org/en-US/docs/Web/API/Node/removeChild
=========================================================
To add something more:
Some answers have pointed out that instead of using parentNode.removeChild(child);, you can use elem.remove();. But as I have noticed, there is a difference between the two functions, and it's not mentioned in those answers.
If you use removeChild(), it will return a reference to the removed node.
var removedChild = element.parentNode.removeChild(element);
console.log(removedChild); //will print the removed child.
But if you use elem.remove();, it won't return you the reference.
var el = document.getElementById('Example');
var removedChild = el.remove(); //undefined
https://developer.mozilla.org/en-US/docs/Web/API/ChildNode/remove
This behavior can be observed in Chrome and FF. I believe It's worth noticing :)
Hope my answer adds some value to the question and will be helpful!!
Functions that use ele.parentNode.removeChild(ele) won't work for elements you've created but not yet inserted into the HTML. Libraries like jQuery and Prototype wisely use a method like the following to evade that limitation.
_limbo = document.createElement('div');
function deleteElement(ele){
_limbo.appendChild(ele);
_limbo.removeChild(ele);
}
I think JavaScript works like that because the DOM's original designers held parent/child and previous/next navigation as a higher priority than the DHTML modifications that are so popular today. Being able to read from one <input type='text'> and write to another by relative location in the DOM was useful in the mid-90s, a time when the dynamic generation of entire HTML forms or interactive GUI elements was barely a twinkle in some developer's eye.
Shortest
I improve Sai Sunder answer because OP uses ID which allows to avoid getElementById:
elementId.remove();
box2.remove(); // remove BOX 2
this["box-3"].remove(); // remove BOX 3 (for Id with 'minus' character)
<div id="box1">My BOX 1</div>
<div id="box2">My BOX 2</div>
<div id="box-3">My BOX 3</div>
<div id="box4">My BOX 4</div>
Having to go to the parent node first seems a bit odd to me, is there
a reason JavaScript works like this?
IMHO: The reason for this is the same as I've seen in other environments: You are performing an action based on your "link" to something. You can't delete it while you're linked to it.
Like cutting a tree limb. Sit on the side closest to the tree while cutting or the result will be ... unfortunate (although funny).
From what I understand, removing a node directly does not work in Firefox, only Internet Explorer. So, to support Firefox, you have to go up to the parent to remove it's child.
Ref: http://chiragrdarji.wordpress.com/2007/03/16/removedelete-element-from-page-using-javascript-working-in-firefoxieopera/
This one actually comes from Firefox... for once, IE was ahead of the pack and allowed the removal of an element directly.
This is just my assumption, but I believe the reason that you must remove a child through the parent is due to an issue with the way Firefox handled the reference.
If you call an object to commit hari-kari directly, then immediately after it dies, you are still holding that reference to it. This has the potential to create several nasty bugs... such as failing to remove it, removing it but keeping references to it that appear valid, or simply a memory leak.
I believe that when they realized the issue, the workaround was to remove an element through its parent because when the element is gone, you are now simply holding a reference to the parent. This would stop all that unpleasantness, and (if closing down a tree node by node, for example) would 'zip-up' rather nicely.
It should be an easily fixable bug, but as with many other things in web programming, the release was probably rushed, leading to this... and by the time the next version came around, enough people were using it that changing this would lead to breaking a bunch of code.
Again, all of this is simply my guesswork.
I do, however, look forward to the day when web programming finally gets a full spring cleaning, all these strange little idiosyncracies get cleaned up, and everyone starts playing by the same rules.
Probably the day after my robot servant sues me for back wages.
// http://javascript.crockford.com/memory/leak.html
// cleans dom element to prevent memory leaks
function domPurge(d) {
var a = d.attributes, i, l, n;
if (a) {
for (i = a.length - 1; i >= 0; i -= 1) {
n = a[i].name;
if (typeof d[n] === 'function') {
d[n] = null;
}
}
}
a = d.childNodes;
if (a) {
l = a.length;
for (i = 0; i < l; i += 1) {
domPurge(d.childNodes[i]);
}
}
}
function domRemove(id) {
var elem = document.getElementById(id);
domPurge(elem);
return elem.parentNode.removeChild(elem);
}
This is the best function to remove an element without script error:
function Remove(EId)
{
return(EObj=document.getElementById(EId))?EObj.parentNode.removeChild(EObj):false;
}
Note to EObj=document.getElementById(EId).
This is ONE equal sign not ==.
if element EId exists then the function removes it, otherwise it returns false, not error.

If a class contains a certain name, change the style of that element

What I currently have in my JS file:
if (documentElement.className("child") != -1){
documentElement.className("child").backgroundColor="red";
}
Basically as the title implies, I want all the classes with the name "child" on the page to change their background color to red.
className returns a string with all of the classes on the element. You need to see if that string contains your class:
if (documentElement.className.indexOf("child") != -1){
Use indexOf
Regarding what #Roberrrt said - you can achieve this simply selecting the 'child class' and applying a style to it.
For a visual example.
http://codepen.io/anon/pen/GNMJjr
In your code:
documentElement.className("child").backgroundColor="red";
That wouldn't work, this is a better way of achieving what you want:
document.querySelector('.child').style.backgroundColor = "red";
I still recommend using CSS. This is redundant and extremely verbose.
Try this maybe (tested on about:blank page with 5 <div> with 2 of them with the class="red" :
var red = [];
red = document.querySelectorAll(".red");
for (var i = 0; i < red.length; i += 1) {
red[i].style.backgroundColor = "red";
}
If you really want to verify if the class name contains a string, use classList.contains (it often have resolved this kind of problem for me, check the MDN page)

Javascript taking too long to run

I have a script that is taking too long to run and that is causing me This error on ie : a script on this page is causing internet explorer to run slowly.
I have read other threads concerning this error and have learned that there is a way to by pass it by putting a time out after a certain number of iterations.
Can u help me apply a time out on the following function please ?
Basically each time i find a hidden imput of type submit or radio i want to remove and i have a lot of them . Please do not question why do i have a lots of hidden imputs. I did it bc i needed it just help me put a time out please so i wont have the JS error. Thank you
$('input:hidden').each(function(){
var name = $(this).attr('name');
if($("[name='"+name+"']").length >1){
if($(this).attr('type')!=='radio' && $(this).attr('type')!=='submit'){
$(this).remove();
}
}
});
One of the exemples i found : Bypassing IE's long-running script warning using setTimeout
You may want to add input to your jquery selector to filter out only input tags.
if($("input[name='"+name+"']").length >1){
Here's the same code optimised a bit without (yet) using setTimeout():
var $hidden = $('input:hidden'),
el;
for (var i = 0; i < $hidden.length; i++) {
el = $hidden[i];
if(el.type!=='radio' && el.type!=='submit'
&& $("[name='" + el.name + "']").length >1) {
$(el).remove();
}
}
Notice that now there is a maximum of three function calls per iteration, whereas the original code had up to ten function calls per iteration. There's no need for, say, $(this).attr('type') (two function calls) when you can just say this.type (no function calls).
Also, the .remove() only happens if three conditions are true, the two type tests and check for other elements of the same name. Do the type tests first, because they're quick, and only bother doing the slow check for other elements if the type part passes. (JS's && doesn't evaluate the right-hand operand if the left-hand one is falsy.)
Or with setTimeout():
var $hidden = $('input:hidden'),
i = 0,
el;
function doNext() {
if (i < $hidden.length) {
el = $hidden[i];
if(el.type!=='radio' && el.type!=='submit'
&& $("[name='" + el.name + "']").length >1) {
$(el).remove();
}
i++;
setTimeout(doNext, 0);
}
}
doNext();
You could improve either version by changing $("[name='" + el.name + "']") to specify a specific element type, e.g., if you are only doing inputs use $("input[name='" + el.name + "']"). Also you could limit by some container, e.g., if those inputs are all in a form or something.
It looks like the example you cited is exactly what you need. I think if you take your code and replace the while loop in the example (keep the if statement for checking the batch size), you're basically done. You just need the jQuery version of breaking out of a loop.
To risk stating the obvious; traversing through the DOM looking for matches to these CSS selectors is what's making your code slow. You can cut down the amount of work it's doing with a few simple tricks:
Are these fields inside a specific element? If so you can narrow the search by including that element in the selector.
e.g:
$('#container input:hidden').each(function(){
...
You can also narrow the number of fields that are checked for the name attribute
e.g:
if($("#container input[name='"+name+"']").length >1){
I'm also unclear why you're searching again with $("[name='"+name+"']").length >1once you've found the hidden element. You didn't explain that requirement. If you don't need that then you'll speed this up hugely by taking it out.
$('#container input:hidden').each(function(){
var name = $(this).attr('name');
if($(this).attr('type')!=='radio' && $(this).attr('type')!=='submit'){
$(this).remove();
}
});
If you do need it, and I'd be curious to know why, but the best approach might be to restructure the code so that it only checks the number of inputs for a given name once, and removes them all in one go.
Try this:
$("[type=hidden]").remove(); // at the place of each loop
It will take a short time to delete all hidden fields.
I hope it will help.
JSFiddle example

Select tags that starts with "x-" in jQuery

How can I select nodes that begin with a "x-" tag name, here is an hierarchy DOM tree example:
<div>
<x-tab>
<div></div>
<div>
<x-map></x-map>
</div>
</x-tab>
</div>
<x-footer></x-footer>
jQuery does not allow me to query $('x-*'), is there any way that I could achieve this?
The below is just working fine. Though I am not sure about performance as I am using regex.
$('body *').filter(function(){
return /^x-/i.test(this.nodeName);
}).each(function(){
console.log(this.nodeName);
});
Working fiddle
PS: In above sample, I am considering body tag as parent element.
UPDATE :
After checking Mohamed Meligy's post, It seems regex is faster than string manipulation in this condition. and It could become more faster (or same) if we use find. Something like this:
$('body').find('*').filter(function(){
return /^x-/i.test(this.nodeName);
}).each(function(){
console.log(this.nodeName);
});
jsperf test
UPDATE 2:
If you want to search in document then you can do the below which is fastest:
$(Array.prototype.slice.call(document.all)).filter(function () {
return /^x-/i.test(this.nodeName);
}).each(function(){
console.log(this.nodeName);
});
jsperf test
There is no native way to do this, it has worst performance, so, just do it yourself.
Example:
var results = $("div").find("*").filter(function(){
return /^x\-/i.test(this.nodeName);
});
Full example:
http://jsfiddle.net/6b8YY/3/
Notes: (Updated, see comments)
If you are wondering why I use this way for checking tag name, see:
JavaScript: case-insensitive search
and see comments as well.
Also, if you are wondering about the find method instead of adding to selector, since selectors are matched from right not from left, it may be better to separate the selector. I could also do this:
$("*", $("div")). Preferably though instead of just div add an ID or something to it so that parent match is quick.
In the comments you'll find a proof that it's not faster. This applies to very simple documents though I believe, where the cost of creating a jQuery object is higher than the cost of searching all DOM elements. In realistic page sizes though this will not be the case.
Update:
I also really like Teifi's answer. You can do it in one place and then reuse it everywhere. For example, let me mix my way with his:
// In some shared libraries location:
$.extend($.expr[':'], {
x : function(e) {
return /^x\-/i.test(this.nodeName);
}
});
// Then you can use it like:
$(function(){
// One way
var results = $("div").find(":x");
// But even nicer, you can mix with other selectors
// Say you want to get <a> tags directly inside x-* tags inside <section>
var anchors = $("section :x > a");
// Another example to show the power, say using a class name with it:
var highlightedResults = $(":x.highlight");
// Note I made the CSS class right most to be matched first for speed
});
It's the same performance hit, but more convenient API.
It might not be efficient, but consider it as a last option if you do not get any answer.
Try adding a custom attribute to these tags. What i mean is when you add a tag for eg. <x-tag>, add a custom attribute with it and assign it the same value as the tag, so the html looks like <x-tag CustAttr="x-tag">.
Now to get tags starting with x-, you can use the following jQuery code:
$("[CustAttr^=x-]")
and you will get all the tags that start with x-
custom jquery selector
jQuery(function($) {
$.extend($.expr[':'], {
X : function(e) {
return /^x-/i.test(e.tagName);
}
});
});
than, use $(":X") or $("*:X") to select your nodes.
Although this does not answer the question directly it could provide a solution, by "defining" the tags in the selector you can get all of that type?
$('x-tab, x-map, x-footer')
Workaround: if you want this thing more than once, it might be a lot more efficient to add a class based on the tag - which you only do once at the beginning, and then you filter for the tag the trivial way.
What I mean is,
function addTagMarks() {
// call when the document is ready, or when you have new tags
var prefix = "tag--"; // choose a prefix that avoids collision
var newbies = $("*").not("[class^='"+prefix+"']"); // skip what's done already
newbies.each(function() {
var tagName = $(this).prop("tagName").toLowerCase();
$(this).addClass(prefix + tagName);
});
}
After this, you can do a $("[class^='tag--x-']") or the same thing with querySelectorAll and it will be reasonably fast.
See if this works!
function getXNodes() {
var regex = /x-/, i = 0, totalnodes = [];
while (i !== document.all.length) {
if (regex.test(document.all[i].nodeName)) {
totalnodes.push(document.all[i]);
}
i++;
}
return totalnodes;
}
Demo Fiddle
var i=0;
for(i=0; i< document.all.length; i++){
if(document.all[i].nodeName.toLowerCase().indexOf('x-') !== -1){
$(document.all[i].nodeName.toLowerCase()).addClass('test');
}
}
Try this
var test = $('[x-]');
if(test)
alert('eureka!');
Basically jQuery selector works like CSS selector.
Read jQuery selector API here.

getElementsByName in IE7

I have some code doing this :
var changes = document.getElementsByName(from);
for (var c=0; c<changes.length; c++) {
var ch = changes[c];
var current = new String(ch.innerHTML);
etc.
}
This works fine in FF and Chrome but not in IE7. Presumably because getElementsByName isn't working in IE. What's the best workaround?
In case you don't know why this isn't working in IE, here is the MSDN documentation on that function:
When you use the getElementsByName method, all elements in the document that have the specified NAME attribute or ID attribute value are returned.
Elements that support both the NAME attribute and the ID attribute are included in the collection returned by the getElementsByName method, but elements with a NAME expando are not included in the collection; therefore, this method cannot be used to retrieve custom tags by name.
Firefox allows getElementsByName() to retrieve elements that use a NAME expando, which is why it works. Whether or not that is a Good Thing™ may be up for debate, but that is the reality of it.
So, one option is to use the getAttribute() DOM method to ask for the NAME attribute and then test the value to see if it is what you want, and if so, add it to an array. This would require, however, that you iterate over all of the nodes in the page or at least within a subsection, which wouldn't be the most efficient. You could constrain that list beforehand by using something like getElementsByTagName() perhaps.
Another way to do this, if you are in control of the HTML of the page, is to give all of the elements of interest an Id that varies only by number, e.g.:
<div id="Change0">...</div>
<div id="Change1">...</div>
<div id="Change2">...</div>
<div id="Change3">...</div>
And then have JavaScript like this:
// assumes consecutive numbering, starting at 0
function getElementsByModifiedId(baseIdentifier) {
var allWantedElements = [];
var idMod = 0;
while(document.getElementById(baseIdentifier + idMod)) { // will stop when it can't find any more
allWantedElements.push(document.getElementById(baseIdentifier + idMod++));
}
return allWantedElements;
}
// call it like so:
var changes = getElementsByModifiedId("Change");
That is a hack, of course, but it would do the job you need and not be too inefficient compare to some other hacks.
If you are using a JavaScript framework/toolkit of some kind, you options are much better, but I don't have time to get into those specifics unless you indicate you are using one. Personally, I don't know how people live without one, they save so much time, effort and frustration that you can't afford not to use one.
There are a couple of problems:
IE is indeed confusing id="" with name=""
name="" isn't allowed on <span>
To fix, I suggest:
Change all the name="" to class=""
Change your code like this:
-
var changes = document.getElementById('text').getElementsByTagName('span');
for (var c=0; c<changes.length; c++) {
var ch = changes[c];
if (ch.className != from)
continue;
var current = new String(ch.innerHTML);
It's not very common to find elements using the NAME property. I would recommend switching to the ID property.
You can however find elements with a specific name using jQuery:
$("*[name='whatevernameYouWant']");
this will return all elements with the given name.
getElementsByName is supported in IE, but there are bugs. In particular it returns elements whose ‘id’ match the given value, as well as ‘name’. Can't tell if that's the problem you're having without a bit more context, code and actual error messages though.
In general, getElementsByName is probably best avoided, because the ‘name’ attribute in HTML has several overlapping purposes which can confuse. Using getElementById is much more reliable. When specifically working with form fields, you can more reliably use form.elements[name] to retrieve the fields you're looking for.
I've had success using a wrapper to return an array of the elements. Works in IE 6, and 7 too. Keep in mind it's not 100% the exact same thing as document.getElementsByName, since it's not a NodeList. But for what I need it for, which is to just run a for loop on an array of elements to do simple things like setting .disabled = true, it works well enough.
Even though this function still uses getElementsByName, it works if used this way. See for yourself.
function getElementsByNameWrapper(name) {
a = new Array();
for (var i = 0; i < document.getElementsByName(name).length; ++i) {
a.push(document.getElementsByName(name)[i]);
}
return a;
}
Workaround
var listOfElements = document.getElementsByName('aName'); // Replace aName with the name you're looking for
// IE hack, because it doesn't properly support getElementsByName
if (listOfElements.length == 0) { // If IE, which hasn't returned any elements
var listOfElements = [];
var spanList = document.getElementsByTagName('*'); // If all the elements are the same type of tag, enter it here (e.g.: SPAN)
for(var i = 0; i < spanList.length; i++) {
if(spanList[i].getAttribute('name') == 'aName') {
listOfElements.push(spanList[i]);
}
}
}
Just another DOM bug in IE:
Bug 1: Click here
Bug 2: Click here

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