I have two DOM elements, A and B, and want to get all style classes from A, and append them to B.
I understand that I can append new classes to element, without wiping existing ones, this way:
B.classList.add("cls1", "cls2", "cls3");
or this way:
var clsa = ["cls1", "cls2", "cls3"];
B.classList.add(...clsa);
Now, my question is, how can I get a list of classes in A, in the form of clsa array?
I can do this by using A.className property, then splitting it into an array.
Or I can simply append A.className to the B.className, as easily as:
B.className += A.className;
Or I can iterate components of A.classList object, 0: ... N:.
The second one looks most natural. However, there's this feeling that the classList, not the className, is the preferred "home" for style classes of an object. Is that right?
And if so, is there any elegant and clear way to do so, without resorting to using className?
Maybe something like:
B.classList.add(...A.classList.all);
Unobvious, but appears to work in Chrome:
B.classList.add(...A.classList);
You can first try to cast classList to an array like it is answered in Why doesn't .includes() work with .classList? , and then append using spread operator.
B.classList.add([...A.classList]);
Related
I've been trying to work out the best way to define a certain element, which is present an arbitrary number of times throughout a page, without requiring:
the 'name' attribute; or
definition of a new element (XHTML).
I am essentially after the 'name' attribute; however, it appears redundant, obsolete and depreciated in parts.
I am hoping to isolate and manipulate said elements using JavaScript, and preferably avoiding jQuery. Is there a reasonable solution? So far I've thought of:
iterating through all elements with a certain tag and checking for a specific className; or
using incremental IDs on the elements (e.g. el1, el2, el3) and iterating through the sequence until getElementById returns null (feels botchy and only sort of what I'm after).
Thanks :)
querySelectorAll returns a list of the elements within the document (using depth-first pre-order traversal of the document's nodes) that match the specified group of selectors. The object returned is a NodeList.
Reference: https://developer.mozilla.org/en/DOM/Document.querySelectorAll
You can use querySelectorAll, and this is an example you can run in javascript console on this page.
var myList = document.querySelectorAll("a");
for (var c= 0 ; c < myList.length; c += 1) {
console.log(myList[c]);
myList[c].onmouseover= function () {alert(this)}
}
If your reference to a className is deliberate, you could use document.getElementsByClassName(), though this isn't supported by IE 8 and earlier. You could fall back on one of your other techniques for those versions. FWIW, I believe this is how jQuery does it.
You can use className - document.getElementsByClassName()
In HTML 5 you can use data attribute - document.querySelectorAll('[...]');
I am wondering if I could use query and javascript together so I could select an element by class with the javascript and then use javascript to work on that element. Sorry if that didn't make sense. Here is an example:
$('.nav_flag').src = "images/flags/"+userCountryLower+".gif";
Would that work, if not how do I get an element by class using regular javascript. Thanks!
EDIT:I know JQUERY is JavaScript but I was wondering if I could mix jquery selectors and javascript 'controller'-for a loss of a better word
To answer your question as asked, there are several ways to take a jQuery object, i.e., what is returned by $('some selector'), and get a reference to the underlying DOM element(s).
You can access the individual DOM elements like array elements:
// update the src of the first matching element:
$(".nav_flag")[0].src = "images/flags/"+userCountryLower+".gif";
// if you're going to access more than one you should cache the jQuery object in
// a variable, not keep selecting the same thing via the $() function:
var navFlgEls = $(".nav_flag");
for (var i = 0; i < navFlgEls.length; i++) { ... }
But you wouldn't manually loop through the elements when you can use jQuery's .each() method, noting that within the callback function you provide this will be set to the current DOM element:
$(".nav_flag").each(function() {
this.src = "images/flags/"+userCountryLower+".gif";
});
However, jQuery provides a way to set attributes with one line of code:
$(".nav_flag").attr("src", "images/flags/"+userCountryLower+".gif");
To answer the second part of your question, doing the same thing without jQuery, you can use .getElementsByClassname() or .querySelectorAll() if you don't care about supporting older browsers.
jQuery IS Javascript. You can mix and match them together. But you better know what you're doing.
In this case, you probably want to use .attr function to set value of attribute.
Use .attr() in jQuery, rather than mix the two here.
$('.nav_flag').attr('src', "images/flags/"+userCountryLower+".gif");
In many instances, it is fine to mix jQuery with plain JavaScript, but if you have already included the jQuery library, you might as well make use of it. Unless, that is, you have an operation which in jQuery would be more computationally expensive than the same operation in plain JavaScript.
You can do it with jQuery too:
$('.nav_flag').attr("src", "images/flags/"+userCountryLower+".gif");
keep in mind that jQuery is simply a library built upon javascript.
for any jQuery object, selecting its elements by subscription will return the corresponding dom element.
e.g.
$('#foo')[0] // is equivalent to document.getElementById('foo');
You need to add an index to the jQuery object to get the native Javascript object. Change:
$('.nav_flag').src = "images/flags/"+userCountryLower+".gif";
To:
$('.nav_flag')[0].src = "images/flags/"+userCountryLower+".gif";
To get elements by class name in Javascript you can use:
document.getElementsByClassName( 'nav_flag' )[0].src = "images/flags/"+userCountryLower+".gif";
To answer your question, you could use .toArray() to convert the jQuery object into an array of standard DOM elements. Then either get the first element or loop through the array to set all the elements with the class.
However, you could do this easier with pure jquery with attr or prop depending on the version:
$('.nav_flag').attr("src", "images/flags/"+userCountryLower+".gif");
Or use pure javascript:
if (navFlagElements = document.getElementsByClassName("nav_flag") && navFlagElements.length > 0) {
navFlagElements[0].src = "images/flags/"+userCountryLower+".gif"
}
I got a div, and there i got some childnodes in undefined levels.
Now I have to change the ID of every element into one div. How to realize?
I thought, because they have upgoing IDs, so if the parent is id='path_test_maindiv' then the next downer would be 'path_test_maindiv_child', and therefore I thought, I'd solve that by wildcards, for example:
document.getElementById('path_test_*')
Is this possible? Or are there any other ways?
Not in native JavaScript. You have various options:
1) Put a class and use getElementsByClassName but it doesn't work in every browser.
2) Make your own function. Something like:
function getElementsStartsWithId( id ) {
var children = document.body.getElementsByTagName('*');
var elements = [], child;
for (var i = 0, length = children.length; i < length; i++) {
child = children[i];
if (child.id.substr(0, id.length) == id)
elements.push(child);
}
return elements;
}
3) Use a library or a CSS selector. Like jQuery ;)
In one of the comments you say:
(...) IE is anyway banned on my page, because he doesn't get it with CSS. It's an admin tool for developer, so only a few people, and they will anyway use FF
I think you should follow a different approach from the beginning, but for what it's worth, in the newer browsers (ok, FF3.5), you can use document.querySelectorAll() with which you can get similar results like jQuery:
var elements = document.querySelectorAll('[id^=foo]');
// selects elements which IDs start with foo
Update: querySelectorAll() is only not supported in IE < 8 and FF 3.0.
jQuery allows you to find elements where a particular attribute starts with a specific value
In jQuery you would use
$('[id^="path_test_"]')
Try this in 2019 as a wildcard.
document.querySelectorAll("[id*=path_test_]")
I don't think so wildcards are allowed in getelementById.
Instead you can have all the child nodes of your respective DIV using:
var childNodeArray = document.getElementById('DIVID').childNodes;
This'll give you an array of all elements inside your DIV. Now using for loop you can traverse through all the child elements and simultaneously you can check the type of element or ID or NAME, if matched then change it as you want.
You should not change ID of element to ID of other existing element. It's very wrong, so you better re-think your core logic before going on.
What are you trying to do exactly?
Anyway, to get all elements with ID starting with something, use jQuery as suggested before, if you can't it's also possible using pure JavaScript, let us know.
I'm trying to find a way that will add / update attribute using JavaScript. I know I can do it with setAttribute() function but that doesn't work in IE.
You can read here about the behaviour of attributes in many different browsers, including IE.
element.setAttribute() should do the trick, even in IE. Did you try it? If it doesn't work, then maybe
element.attributeName = 'value' might work.
What seems easy is actually tricky if you want to be completely compatible.
var e = document.createElement('div');
Let's say you have an id of 'div1' to add.
e['id'] = 'div1';
e.id = 'div1';
e.attributes['id'] = 'div1';
e.createAttribute('id','div1')
These will all work except the last in IE 5.5 (which is ancient history at this point but still is XP's default with no updates).
But there are contingencies, of course.
Will not work in IE prior to 8:e.attributes['style']
Will not error but won't actually set the class, it must be className:e['class'] .
However, if you're using attributes then this WILL work:e.attributes['class']
In summary, think of attributes as literal and object-oriented.
In literal, you just want it to spit out x='y' and not think about it. This is what attributes, setAttribute, createAttribute is for (except for IE's style exception). But because these are really objects things can get confused.
Since you are going to the trouble of properly creating a DOM element instead of jQuery innerHTML slop, I would treat it like one and stick with the e.className = 'fooClass' and e.id = 'fooID'. This is a design preference, but in this instance trying to treat is as anything other than an object works against you.
It will never backfire on you like the other methods might, just be aware of class being className and style being an object so it's style.width not style="width:50px". Also remember tagName but this is already set by createElement so you shouldn't need to worry about it.
This was longer than I wanted, but CSS manipulation in JS is tricky business.
Obligatory jQuery solution. Finds and sets the title attribute to foo. Note this selects a single element since I'm doing it by id, but you could easily set the same attribute on a collection by changing the selector.
$('#element').attr( 'title', 'foo' );
What do you want to do with the attribute? Is it an html attribute or something of your own?
Most of the time you can simply address it as a property: want to set a title on an element? element.title = "foo" will do it.
For your own custom JS attributes the DOM is naturally extensible (aka expando=true), the simple upshot of which is that you can do element.myCustomFlag = foo and subsequently read it without issue.
How do I get an element or element list by it's tag name. Take for example that I want all elements from <h1></h1>.
document.getElementsByTagName('a') returns an array. Look here for more information: http://web.archive.org/web/20120511135043/https://developer.mozilla.org/en/DOM/element.getElementsByTagName
Amendment: If you want a real array, you should use something like Array.from(document.getElementsByTagName('a')), or these days you'd probably want Array.from(document.querySelectorAll('a')). Maybe polyfill Array.from() if your browser does not support it yet. I can recommend https://polyfill.io/v2/docs/ very much (not affiliated in any way)
Use $$() and pass in a CSS selector.
Read the Prototype API documentation for $$()
This gives you more power beyond just tag names. You can select by class, parent/child relationships, etc. It supports more CSS selectors than the common browser can be expected to.
Matthias Kestenholz:
getElementsByTagName returns a NodeList object, which is array-like but is not an array, it's a live list.
var test = document.getElementsByTagName('a');
alert(test.length); // n
document.body.appendChild(document.createElement('a'));
alert(test.length); // n + 1
You could also use $$(tag-name)[n] to get specific element from the collection.
If you use getElementsByTagName, you'll need to wrap it in $A() to return an Array. However, you can simply do $$('a') as nertzy suggested.