I'm quite new to javascript and JQuery programming. Usually, to access elements I give them an id, so I can get them like $("#"+id).blabla().
But now I need to dynamically create a div, and access elements inside it.
Something like
<div id="automaticallyGeneratedId">
<div ???></div> <!-- first div -->
<div ???></div> <!-- second div -->
</div>
What are the best practices to access and identify each of the inner divs?
I generate another id for them?
Or what?
I don't have the theory of selectors fully clear.
edit: modified the question from identifying a single inner div to identifying divs amongs many of them
You can maintain a pattern when you're generating id. For example:
if you always generate id like: myid1, myid2,myid3...
<div id="myid1">
<div></div>
</div>
<div id="myid2">
<div></div>
</div>
......
then you can try:
$('div[id^=myid]').find('div').foo();
OR
$('div[id^=myid] div').foo();
Here, ^= is start with selector, so div[id^=myid] will select div whose id start with myid.
You can also use Contain word selector which is ~= and use like $('div[id~=myid]'). This will select div with id contains word myid.
Instead of id if you want to use other attribute eg. name then change selector like:
$('div[name^=myid]') or $('div[name~=myid]').
It's usually a good practice that if you already have a reference to that outer div to just search from there using find.
You can give it an id, or if you want to use a more general approach you can use classes.
<div class="subdiv">...
$('#automaticallyGeneratedId').find('div.subdiv')
Usually, when you create them, you can assign event handlers and the likes straight on them. Like this:
var div = $( '<div></div>' );
div.on( 'click', function() {
// Do something when the generated div is clicked
});
// Then, add it to the DOM
$( 'body' ).append( div );
You don't need to bother selecting them with ID or classes, they're already available in your code.
Another way is to use event bubbling to handle newly created elements of the same class. A good link about this is this one: http://beneverard.co.uk/blog/understanding-event-delegation/
Many ways you can create an element and give him an Id or Class, or use the DOM to access it..
$("html").prepend('<div id="foo"></div>');
$("#foo").doSomething();
another way
$("#automaticallyGeneratedId").find("div").doSomething();
To access the div in the element with the id:
$("#automaticallyGeneratedId div").whatever
If you cache the divs you could use something like:
var myDiv1Child = $('div', myDiv1);
Create a delegated listener and within the listener you can find the element by doing this
//If a div inside the parent is clicked then execute the function within
$('.PARENT_CLASS').click("div", function(){
//This variable holds all the elements within the div
var rows = document.querySelector('.PARENT_CLASS').getElementsByTagName('div');
for (i = 0; i < rows.length; i++) {
rows[i].onclick = function() {
console.log(this); //The element you wish to manipulate
}
}
});
Related
I am writing a small library where I am in need of selecting a relative element to the targeted element through querySelector method.
For example:
HTML
<div class="target"></div>
<div class="relative"></div>
<!-- querySelector will select only this .target element -->
<div class="target"></div>
<div class="relative"></div>
<div class="target"></div>
<div class="relative"></div>
JavaScript
var target = document.querySelectorAll('.target')[1];
// Something like this which doesn't work actually
var relativeElement = target.querySelector('this + .relative');
In the above example, I am trying to select the .relative class element relative only to the .target element whose value is stored in target variable. No styles should apply to the other .relative class elements.
PS: the selectors can vary. So, I can't use JavaScript's predefined methods like previousElementSibling or nextElementSibling.
I don't need solution in jQuery or other JavaScript libraries.
Well it should be ideally:
var relativeElement = target.querySelector('.relative');
But this will actually try to select something inside the target element.
therefore this would only work if your html structure is something like:
<div class="target">
<div class="relative"></div>
</div>
Your best bet would probably in this case be to use nextElementSibling which I understand is difficult for you to use.
You cannot.
If you insist on using the querySelector of the subject element, the answers is there is no way.
The spec and MDN both says clearly that Element.querySelector must return "a descendant of the element on which it is invoked", and the object element you want does not meet this limitation.
You must go up and use other elements, e.g. document.querySelector, if you want to break out.
You can always override Element.prototype.querySelector to do your biddings, including implementing your own CSS engine that select whatever element you want in whatever syntax you want.
I didn't mention this because you will be breaking the assumption of a very important function, easily breaking other libraries and even normal code, or at best slowing them down.
target.querySelector('.relative');
By using querySelector on the target instead of document, you scope the DOM traversal to the target element.
It is not entirely clear from your explanation, but by related i assume you mean descendant?
To get all target elements you can use
document.querySelectorAll('.target')
And then iterate the result
I found a way which will work for my library.
I will replace "this " in the querySelector with a unique custom attribute value. Something like this:
Element.prototype.customQuerySelector = function(selector){
// Adding a custom attribute to refer for selector
this.setAttribute('data-unique-id', '1');
// Replace "this " string with custom attribute's value
// You can also add a unique class name instead of adding custom attribute
selector = selector.replace("this ", '[data-unique-id="1"] ');
// Get the relative element
var relativeElement = document.querySelector(selector);
// After getting the relative element, the added custom attribute is useless
// So, remove it
this.removeAttribute('data-unique-id');
// return the fetched element
return relativeElement;
}
var element = document.querySelectorAll('.target')[1];
var targetElement = element.customQuerySelector('this + .relative');
// Now, do anything with the fetched relative element
targetElement.style.color = "red";
Working Fiddle
I run into this problem frequently and never know the best approach. Imagine I have a structure that includes several instances of the following html:
<div class="known">
<div class="another unknown">
<div class="unknown">
<h4>Something a something</H4>
</div>
</div>
</div>
For each div of class known, I want to change the inner html of that div only if it contains a div inside it with some particular tag, in this case <h4>.
What is the best way to achieve that. I know that I could do it by taking the inner html of class known and doing a regex match. But is there a more robust way based on tags?
Simple, just use a selector that spans over the div.known and restrict it's context to div h4. If the selector selects at lease one element then the div.class has children as you expect.
if( $('.known div h4').length > 0 ){
$('.known').html('Some html');
}
Yes! You can do this.
var head = Array.prototype.slice.call(document.querySelectorAll("h4 #known"));
for(var i = 0; i < head.length; i++)
{
while(head[i].className !== "known")
head[i] = head[i].parent();
}
Now head will be an array of all the DOM elements have the tag known and have h4's in them.
With jQuery, you can use .has() to narrow your selection and even chain other methods, as in:
$(".known").has("h4").css("background","red");
Check out this fiddle for example. Notice that clicking the button will change the color of any div.known only if that element contains an h4 tag as a descendant.
Documentation on jQuery's .has() -- https://api.jquery.com/has/
I have a list of divs in the following structure, where the text in the a.status-progress will either say "in progress" or "not started":
<div class="plan-section">
<div class="tableView-row">
<p class="plan-name">
<a>some name</a>
</p>
<a class="status-progress">in progress</a>
</div>
</div>
<!-- same structure as above but not expanded -->
<div class="plan-section"></div>
<div class="plan-section"></div>
All the <a> tags with in each <div> act as links. What I would like to do is loop through each div, check and see if the a.progress has the string "in progress" with in it . If it doesn't I want to remove the cursor:pointer css property and any events attached to the <a> tags. Current my jQuery implementation is:
// remove linking if plan is not joined
$('.status-progress').each(function(i){
var planLinks = $('.status-progress, .plan-name a');
var planStatus = $(this).text();
if (planStatus === "in progress"){
planLinks.css('cursor','pointer')
}
});
This is not working properly though because I believe my logic with the each() is wrong or that I need to add another one later in the code block. Thanks for the help!
EDIT: Added proper class for status-progress
The line:
var planLinks = $('.status-progress, .plan-name a');
...will select all such anchor elements, not just the ones related to the current iteration of the .each() loop. One way to get just the related ones is:
var planLinks = $(this).closest("div").find("a");
That is, use DOM traversal methods to find the containing div and then select the anchors within it. Or you could go based on siblings, etc., but that is more fragile since a change to the html structure is then more likely to require a change to the JS.
But you don't really need the .each() loop if you do something like this instead:
$("a.status-progress:contains('in progress')") // find the 'in progress' anchors
.closest("div") // get their containing divs
.find("a") // find the anchors in those divs
.off() // remove the event handlers
.css('cursor','pointer'); // set the CSS property
I have two different divs
var promptContent = $('<div id="errorr">').addClass("formErrorContent").html(promptText).appendTo(prompt);
var arrow = $('<div id="errorrarrow">').addClass("formErrorArrow");
I want to use their id in javascript like this
function windowclose()
{
document.getElementById('add_project').style.display="none";
document.getElementById('blanket').style.display="none";
document.getElementById('errorr').style.display="none";
document.getElementById('errorrarrow').style.display="none";
// $("#blanket").fadeIn("none");
// $("#add_project").fadeIn("none");
}
But here it hides only the 1st div. I want to hide all the divs with the same id. How can I do this?
Choose between to use name or id:
getElementsByName('errorr') searches in the DOM an element named errorr
getElementById('errorr') searches in the DOM an element with the id equals to errorr;
Try to change your code:
document.getElementsByName('errorr').style.display="none";
document.getElementsByName('errorrarrow').style.display="none";
to
document.getElementById('errorr').style.display="none";
document.getElementsById('errorrarrow').style.display="none";
also note that a DOM must have all unique IDs (as rule)
UPDATE:
Well, if you need to hide a set of divs I usually add at all of them a class like .element-to-hide:
<div id="asd" class="element-to-hide">...
<div id="lol" class="element-to-hide">...
<div id="foo" class="element-to-hide">...
Ant after just a touch of jQuery:
$('.element-to-hide').each(function(){
$(this).hide();
});
Hope this help
Even though using the same ID on many elements is semantically invalid, you could do it in a single jQuery line.
$('#errorr, #errorrarrow').hide();
<div onclick="test(this)">
Test
<div id="child">child</div>
</div>
I want to change the style of the child div when the parent div is clicked. How do I reference it? I would like to be able to reference it by ID as the the html in the parent div could change and the child won't be the first child etc.
function test(el){
el.childNode["child"].style.display = "none";
}
Something like that, where I can reference the child node by id and set the style of it.
Thanks.
EDIT: Point taken with IDs needing to be unique. So let me revise my question a little. I would hate to have to create unique IDs for every element that gets added to the page. The parent div is added dynamically. (sort of like a page notes system). And then there is this child div. I would like to be able to do something like this: el.getElementsByName("options").item(0).style.display = "block";
If I replace el with document, it works fine, but it doesn't to every "options" child div on the page. Whereas, I want to be able to click the parent div, and have the child div do something (like go away for example).
If I have to dynamically create a million (exaggerated) div IDs, I will, but I would rather not. Any ideas?
In modern browsers (IE8, Firefox, Chrome, Opera, Safari) you can use querySelector():
function test(el){
el.querySelector("#child").style.display = "none";
}
For older browsers (<=IE7), you would have to use some sort of library, such as Sizzle or a framework, such as jQuery, to work with selectors.
As mentioned, IDs are supposed to be unique within a document, so it's easiest to just use document.getElementById("child").
This works well:
function test(el){
el.childNodes.item("child").style.display = "none";
}
If the argument of item() function is an integer, the function will treat it as an index. If the argument is a string, then the function searches for name or ID of element.
If the child is always going to be a specific tag then you could do it like this
function test(el)
{
var children = el.getElementsByTagName('div');// any tag could be used here..
for(var i = 0; i< children.length;i++)
{
if (children[i].getAttribute('id') == 'child') // any attribute could be used here
{
// do what ever you want with the element..
// children[i] holds the element at the moment..
}
}
}
document.getElementById('child') should return you the correct element - remember that id's need to be unique across a document to make it valid anyway.
edit : see this page - ids MUST be unique.
edit edit : alternate way to solve the problem :
<div onclick="test('child1')">
Test
<div id="child1">child</div>
</div>
then you just need the test() function to look up the element by id that you passed in.
If you want to find specific child DOM element use method querySelectorAll
var $form = document.getElementById("contactFrm");
in $form variable we can search which child element we want :)
For more details about how to use querySelectorAll check this page