JavaScript String .replace method is replacing all my content? - javascript

I have successfully implemented finding and replacing some text with something else in the following way:
$(".class").html($(".class").html().replace(/\text\b/g, '<span class="newclass newclass2">new text</span>'));
When I apply this to my element 'class' it finds all the 'text' and replaces with 'new text' and everything relating to the new classes.
However, if I have more than one element on the page with the same class, it replaces all the classes with whatever text is in the first class.
For example, if my first class has the content "Hello everyone", when the script is applied to this class, it works fine. Any subsequent class of the same name is then replaced with "Hello everyone". These also have the function applied in the same way as the first occurrence of that class.
IE, it applies the script, then replicates this in every single class of the same name on the page.
I do not understand why it would do this, and rather renders the function pointless in many ways if it can't be used to change text throughout different sections without setting up new scripts and different classes.
Hopefully there is something simple at work here that I am not aware of, any help would be much appreciated.
Many thanks
Richard

That is the nature of class selectors--the .html(...) will replace the HTML of everything that matches the .class selector.
If you want to replace text in each individual .class element, you can use the .each function. (There are probably jQuerier ways, too.)
$(`.class`).each(function(n, el) {
var myHtml = $(this).html();
myHtml = mungeIt(myHtml);
$(this).html(myHtml);
});
If you want to select only an individual .class element, then you either (a) don't really want to be using classes, but IDs, or (b) need to understand enough of your structure or the context you wish to operate in to select only the targeted DOM element.
(And hope the structure or context doesn't change without a corresponding code update.)

You're specifying a class with the jQuery selector $(".class") That's what the period indicates. jQuery has a ton of selectors to choose from. A list is provided in the documentation here: http://api.jquery.com/category/selectors/
Also, I'd look at http://api.jquery.com/hasClass/ for your problem as you could then use if...then statements to not run into others

Dave is right about needing to use the .each method. We need to loop through each element at a time because .html() will only return the first element when there are multiple matches.
Try:
$('.class').each(function() {
$(this).html($(this).html().replace(/someWord/g,'withAnother'));
});

Related

How to use common js function for two divs containig elements of identical ids?

I have common jQuery function and two div tags. Both div tags have different names but both containing elements of identical ids now i want to use this common Jquery function for them both?
I have implemented common function but it's not working for both.
Here's link to my jsfiddle -jsfiddle.net/xS7zF/1/
In my jsfiddle there are two div tags namely example1 and example2 and both tags have elements of identical ids. Function is working fine for first div but not for second.
please help me to sort out this.
Yeah, under the hood, jQuery selection on an ID will use the Document.GetElementById() function implemented by the browser, which is really fast, but (i guess depending on the browser) will stop after it finds the first element, since ID's should be unique and no further searching is needed after the first one is found.
For instance, rename the divs with id="eb" to class="eb" and you can still target specific elements using $("#example1 .eb") and $("#example2 .eb")
UPDATE:
Using your new Fiddle I created this: http://jsfiddle.net/xS7zF/5/
I cleaned up a lot of code and hopefully you can see what I have done. I changed all elements that appear twice from id to class. Now, when you attach an event to an element using $(".classname").click(), it attaches to all the elements. In the handler function where you set HTML and do your show()/hide(), you don't target a specific element using it's ID, but you find it relative to the element that does the event. You can do this using parent(), parentsUntil(), next(), find(), etc. Check jQuery docs for all possibilities. So for instance, the change-handler attaches to all inputs with name=Assets. But instead of doing $("#b1").show(), I go to the parent of the specific input that fires using $(this).parent(). Then I find the element with a class=".b1", which it will only find the one that is next to this specific input and I set the HTML to just that element.
Since there is another input, the same actions happen when THAT input changes, but instead it finds IT's parent, and finds the element with class=".b1" that is next to IT. So both divs with input are contained since they act on elements relative to itself and not across the document.
For extra fun and to show you how flexible this way of programming is, here is a fiddle with the Javascript-code unchanged, but with the exact same question-div copied 8 times. No matter how many times you repeat this, the same code will act on as many divs as you create since everything works relative. http://jsfiddle.net/xS7zF/7/
Hopefully this helps, the rest is up to you!
ID's must be unique, you should not repeat them. You could replace id with class and in the jQuery function do (".ub").each() or manually referencing the object using eq(x). e.g. (".ub").eq(1).
You shouldn't assign same id's to different elements.
You CAN but you SHOULDN'T. Instead of giving the same id, use class
IDs must be unique, try fix this, change to classes.
You can try something like this:
$("div div:first-child")
instead of
$("#eb")
But depends of the rest of your page code. So, change to classes first and use
$(".eb")
when jQuery / javascript find the first ID it would ignore the rest, please read more about it
http://www.w3schools.com/tags/att_global_id.asp

How to get element from template by javascript?

I dont know good method how to get DOM element from template by javascript.
Example template:
<script id = "template" type="text/template">
<div>text1</div>
<div>text2</div>
<div>text3</div>
</script>
For example i want get div with "text2"
There is ways which i know, all of them are bad:
Add "class" to all elements - it breaks semantics (class created for CSS). In big projects you must use very long names for classes, its very inconvenient.
Get element by his number (index) - when adding a new element, you must rewrite old numbers in your code.
I see a couple of options:
If you don't want to use class , you can use a data-* attribute.
Assuming you load the template once and then duplicate its contents as desired, you could put id values on the elements in the template, which you then remove when cloning them and adding them to the document (so you don't end up with the same id on more than one copy of the element, which would be invalid and probably counterproductive).
Maybe you can also create as many templates as you need.
One for each div.
If you need to get each div at a time you must set ids to them ... of course you can also browse the dom inside script element to find the one you're interested in ...
Home this helps
Regards
mimiz

How can I access a particular div on a page which has the same id in two places?

This is the same question as this:
Referring to a div inside a div with the same ID as another inside another
except for one thing.
The reason there are two elements with the same ID is because I'm adding rows to a table, and I'm doing that by making a hidden div with the contents of the row as a template. I make a new div, copy the innerhtml of the template to my new div, and then I just want to edit bits of it, but all the bits have the same ID as the template.
I could dynamically create the row element by element but it's a VERY complex row, and there's only a few things that need to be changed, so it's a lot easier to just copy from a template and change the few things I need to.
So how do I refer to the elements in my copy, rather than the template?
I don't want to mess up the template itself, or I'll never be able to get at the bits for a second use.
Or is there another simpler way to solve the problem?
It will probably just be easiest when manipulating the innerHtml to do a replace on the IDs for that row. Maybe something like...
var copiedRow = templateRow.innerHTML.replace(/id=/g,"$1copy")
This will make the copied divs be prefixed with "copy". You can develop this further for the case that you have multiple copies by keeping a counter and adding that count variable to the replace() call.
When you want to make a template and use it multiple times its best to make it of DOM, in a documentFragment for example.
That way it doesn't respond to document.getElementById() calls in the "live" DOM.
I made an example here: http://jsfiddle.net/PM5544/MXHRr/
id's should be unique on the page.
PM5544...
In reality, there's no use to change the ID to something unique, even though your document may not be valid.
Browsers' selector engines treat IDs pretty much the same as class names. Thus, you may use
document.querySelector('#myCopy #idToLookFor');
to get the copy.
IDs on a page are supposed to be unique, even when you clone them from a template.
If you dynamically create content on your page, then you must change the id of your newly cloned elements to something else. If you want to access all cloned elements, but not the template, you can add a class to them, so you can refer to all elements with that class:
var clonedElement = template.cloneNode(yes); // make a deep copy
clonedElement.setAttribute("id", "somethingElse"); // change the id
clonedElement.setAttribute("class",
clonedElement.getAttribute("class") + " cloned"
);
To access all cloned elements by classname, you can use the getElementsByClassName method (available in newer browsers) or look at this answer for a more in-depth solution: How to getElementByClass instead of GetElementById with Javascript?
Alternatively, if you have jQuery available, you can do this is far less lines of code:
$("#template").clone().attr("id","somethingElse")
.addClass("cloned").appendTo("#someDiv");
The class lookup is even simpler:
$(".cloned").doSomethingWithTheseElements();
Try to avoid using IDs in the child elements of the cloned structure, as all ids of the cloned element should be changed before adding the clone to the page. Instead, you can refer to the parent element using the new id and traverse the rest of the structure using classnames. Class names do not need to be unique, so you can just leave them as they are.
If you really must use ID's (or unique "name" attributes in form fields), I can strongly suggest using a framework like jQuery or Prototype to handle the DOM traversal; otherwise, it is quite a burden to resolve all the cross-browser issues. Here is an example of some changes deeper in the structure, using jQuery:
$("#template").clone().attr("id","somethingElse")
.addClass("cloned") // add a cloned class to the top element
.find("#foo").attr("id","bar").end() // find and modify a child element
.appendTo("#someDiv"); // finally, add the node to the page
Check out my ugly but functional cheese. I wrote a function that works like getelementbyid, but you give it a start node instead of the document. Works like a charm. It may be inefficient but I have great faith in the microprocessors running today's browsers' javascript engines.
function getelement(node, findid)
{
if (node)
if (node.id)
if (node.id == findid)
return node;
node = node.firstChild;
while(node)
{
var r = getelement(node, findid);
if (r != null)
return r;
node = node.nextSibling;
}
return null;
}
When you copy the row, don't you end up having a reference to it? At that point can't you change the ID?

Will jQuery search for the ID before filtering other parameters in the selector?

This question is related to performance.
If I use a selector like the following
$('#myID a') // Does this find #myID and filter by a?
Or should I write the statement like this?
$('#myID').find('a')
I'm not sure if jQuery is smart enough to execute this statement using the ID first or if it operates exactly like CSS and reads right to left. It's not such a big deal using tags but when you run something like
$('#myID .myClass')
It makes a HUGE difference in performance.
From a NetTuts article: http://net.tutsplus.com/tutorials/javascript-ajax/quick-tip-think-right-to-left-with-jquery/
As an example, if Sizzle comes across a selector like $('#box p'),
it’s true that it works right-to-left, but there’s also a quick regex
optimization that will first determine whether the first section of
the selector is an id. If so, it’ll use that as the context, when
searching for the paragraph tags.
Relevant comment from SizzleJS:
// Take a shortcut and set the context if the root selector is an ID
// (but not if it'll be faster if the inner selector is an ID)
When an Id is in the selector. jQuery will first execute document.getElementById then begin filtering for child elements.
basically this is why it is never a great idea to use just attribute or class selectors $('.someclass') or $('[name=myname]') without being more specific. Because it causes the code to traverse the DOM and look at every element to find that class.
By just adding a tagname to the same selector $('div.someclass') or $('div.[name=myname]') you improve efficiency becuase it will first run. document.getElementsByTagName narrowing the number of elements to search.

Prototype.js get text from an element

I'm new to Protoype.JS and just testing it a bit because I heard it was good, but I'm stuck quite quickly.
As easy as this is with jQuery, it seems to be the end of the world to get the text in an element. I've tried innerHTML in multiple ways but the only thing I can get is "undefined".
alert($$('.mnu_item').innerHTML);
alert($('content').innerHTML);
None of these work.
Content is a div with id "content" and .mnu_item is an anchor tag with class ".mnu_item".
I don't get what the problem is, probably something stupid but it would be great if somebody could point me in the right direction!
EDIT: I've found that it isn't the innerHTML that doesn't work but it's the class selector. The second line in the code above does work. How can I select an element by its class in the latest Prototype version if this isn't the correct way?
Has the DOM loaded when you run your script? If you're not running this code in a window.onload or by placing it at the end of the body, then the elements by not exist when it runs.
Try placing your script just inside the closing </body> tag.
<body>
<!-- my content -->
<script type="text/javascript">
alert($('content').innerHTML);
</script>
</body>
Also, your first line is selecting correctly, but will return an Array of elements, so innerHTML will be undefined.
To iterate the Array, you can do this:
$$('.mnu_item').each(function(val,i) {
alert(val.innerHTML);
});
or if you want to end up with an Array of the innerHTML values, do this:
var values = $$('.mnu_item').map(function(val,i) {
return val.innerHTML;
});
Make sure the DOM is loaded before you run these tests:
$(document).on('dom:loaded', function () {
/* code to execute after dom has loaded */
})
The first line of code $$('.mne_item') doesn't work because $$ gives back an array of all elements matching the css rule. So $$('.mne_item') gives an array of all dom elements which has the class mne_item. You can ask the first one by using the first method or iterate over all items like this:
$$('.mne_item').each(function(elem) {
// elem is the li elements extended by all Element methods of prototype
});
If you use $ in jQuery, it actually uses a similar pattern but hides the each construct. It just applies the chained method to all elements or just the first.
The second line of code $('content').innerHTML should work. $ is a shortcut for document.getElementById so it should give you a DOM node back. The reason why this doesn't work is there is no node where id = content, probably because the dom isn't loaded yet.
For more info about the methods of prototype look at the api: http://api.prototypejs.org/
Also check the default DOM methods: http://quirksmode.org/dom/w3c_core.html
$('content').innerHTML should work. Check your HTML, ensure the ID is unique.
var text = $$('label[for="display_on_amazon"]').first().textContent;
Above code worked for me.
Regarding, $$('.mnu_item').innerHTML
When you are trying to fetch with class selector, prototype returns array of multiple elments, by using [0] or first() method system will point at the first element in that array, after that you can use innerHtml (to get html inside the element) or textContent (to get text content of that element, native javascript method)

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