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How to set active TAB /active/color-changed or whatever similar event on the selected TAB

I know it has been explained in many places here but I can't get it to work.
It concerns: how to use JavaScript which is in - under wwwroot created - folder in a *.js file.
What I am using:
Blazor Server App empty (VS2022, C#).
I only need/use Server App in VS2022 C# and empty - without any predefined navbars and other elements. So there are no any *.cshtml files except one which is automatically created while creating a "Blazor Server App Empty" in VS 2022 and that is "_Host.cshtml"
And I don't want to use any other template in VS 2022, only this one mentioned.
So, after creating a "page" using this in VS integrated template, I added following in MainLayout.razor (I am using *razor and only razor - no any cshtml):
// this was originally created as in the template in VS2022
#inherits LayoutComponentBase
//this one also:
<main> #Body </main>
// That is what I added here in MainLayout.razor, it's from this site: [http://jsfiddle.net/Ag47D/3/](https://www.stackoverflow.com/)
<div class="navbar">
<div class="navbar-fixed-top">
<div class="container" style="width: auto;">
<div class="nav-collapse" id="nav-collapse">
<ul class="nav" id="nav">
<li id="home">Home</li>
<li id="skill">Skill</li>
<li id="research">Research</li>
<li id="link">Link</li>
</ul>
</div>
</div>
</div>
</div>
And then I added the css part to the existing "site.css" in that simply VS 2022 project:
`.navbar #nav > .active > a {
color: red;
}`
And finally - and that is the big issue for me to understand WHRE/HOW to handle that . a simply JavaScript part (you can find that on the same site mentioned):
` $(function() {
$('#nav li a').click(function() {
$('#nav li').removeClass();
$($(this).attr('href')).addClass('active');
});
});`
I added that to a created folder in wwwroot, the flder is called: "js" and the file inside that folder is called: "setactivetab.js". In that file is the mentioned part of javascript.
In "_Host.cshtml" I added then that, here the part of that _Host.cshtml where you can see what I added:
`....
....
Reload
<a class="dismiss">🗙</a>
</div>
<script src="~js/setactivetab.js"></script>
<script src="_framework/blazor.server.js"></script>
</body>
</html>`
So I tried with:
<script src="~js/setactivetab.js"></script>
and:
<script src="js/setactivetab.js"></script>
and:
<script src="~/js/setactivetab.js"></script>
But nothing worked. I mean: TABS are shown on the page - no question about that - but if I click on one of that TABs - nothing happens, the color isn't changed.
Somehow I am not able to understand how to use a self created/from google downloaded, JavaScript for simply changing of the color or to set a selected TAB as active/current or however we can use that.
I tried so many examples described on the web. I can't get that working - maybe I am missing/not understood some fundamental knowledge of using a JavaScript. I simply don't know the way how one can use that.
Can you please post me here a working example of a navigation TABS, ideally self created and simply? Important is: WHERE to put a javascript and how to access that properly so the clicking on a TAB wil lchange his color and stay so until I click on another TAB in a simply - if possible: horizontal, not vertical, navigation bar.
I have enough from searching/reading of many web sites descriptions as there works all and if I copy&paste some simply example, it doesn't work.

How to scroll to element after click event and new page load with Vanilla JavaScript

I will try to summarize this in a Requirements fashioned way, I hope this simplifies the question.
When clicking on an anchor tag, the web page navigates the user to a new page, where upon page load, the page is scrolled to the element which corresponds to the aforementioned anchor tag, which was previously clicked.
As you will see in the code I am trying to make use of the CSS scroll-behaviour property.
https://developer.mozilla.org/en-US/docs/Web/CSS/scroll-behavior
So far I have tried out the code bellow, however when I run it I get an error message in the developer console stating:
TypeError: Cannot read property 'offsetTop' of undefined
Hence, I surmise that the window.onload function is not really fired on the page which I would like to load but the very same page on which I am located when clicking the anchor tag. How can I change the code so it would count for page intended.
HTML of Page A (where the anchor tag is located):
<a id="ship-it" href="services.html" class="services">
<div id="image-container_4">
<div id="image_4">
<div id="overlay_4"></div>
<h2 class="h2">We pack it and ship it</h2>
<img id=imageB src="/images/shipping.jpg" alt="">
</div>
</div>
</a>
HTML of Page B (where the target element is located):
<section id="manufacturing-section" class="section">
<img src="/images/manufacturingMelting2.jpg" alt="Magnetic Particle Inspection">
<div id="manufacturing-container">
<h2> <span>Manufacturing</span> <br> We provide high quality, low cost solutions to meet your requirements.</h2>
<p>
soemthing something something, DarkSide...
</p>
</div>
</section>
JS / CSS:
function scrollIt(element) {
window.scrollTo({
'behavior': 'smooth',
'left': 0,
'top': element.offsetTop
});
}
const serviceAnchor = document.querySelectorAll('.services');
//'serviceAnchor' is located on page A
const sections = document.querySelectorAll('.section');
// 'sections' is located on page B and represents the element the page should scroll to when the page has loaded after the corresponding anchor tag was clicked
serviceAnchor[0].addEventListener('click', () => {
window.onload = scrollIt(sections[0]);
});
serviceAnchor[1].addEventListener('click', () => {
window.onload = scrollIt(sections[1]);
});
serviceAnchor[2].addEventListener('click', () => {
window.onload = scrollIt(sections[2]);
});
serviceAnchor[3].addEventListener('click', () => {
window.onload = scrollIt(sections[3]);
});

The reason you're getting the error is it's impossible to run javascript across page loads. Assuming you're using a traditional site and not a single-page app, when the browser loads a new page, all javascript on the current page is stopped.
Browsers already support jumping to an element on page load using the www.site.com#myElementId syntax. If you want smooth scrolling, you'll need to pass the id of element to scroll in the url, or some other way like caching its id in localstorage, then run your smooth scrolling js on the pageload of the other page.

You can't navigate to a different page and then ask the browser to launch a piece of JavaScript. That would be a huge security issue, since I could make you click into a link to, let's say, my-bank.com then do a bit of JavaScript do access your secret cookies or local storage and hack into your account.
The only thing you can do is link to anchors inside the linked page, and the default scroll behavior (no smooth scrolling, for most browsers, since it's the least computationally and resources intensive) will be used:
<!-- not possible -->
<a onclick="navigateThenDoSomething()">Some link</a>
<!-- possible -->
Some link
If you own the target page, however, you can hide a target section in the query string then do a bit of magic in the target page's onload to smoothly scroll to your section:
<!-- source-page.html -->
Some link
// script running at target-page.html
const url = new URL(window.location);
const section = url.searchParams.get('section');
if (section) {
// scroll smoothly to `section` using
}

Since .scrollTo JS method with options has the same browser compatibility as scroll-behavior CSS property, and you're OK with that, you might get rid of your JS code and set:
html, body, .or-other-scrolling-container {scroll-behavior:smooth}
and use anchor links.
So HTML of Page A would be e.g.:
<a id="ship-it" href="services.html#manufacturing" class="services">
<div id="image-container_4">
<div id="image_4">
<div id="overlay_4"></div>
<h2 class="h2">We pack it and ship it</h2>
<img id=imageB src="/images/shipping.jpg" alt="">
</div>
</div>
</a>
And HTML of Page B (please note <a name="#manufacturing"> tag):
<a name="manufacturing"></a>
<section id="manufacturing-section" class="section">
<img src="/images/manufacturingMelting2.jpg" alt="Magnetic Particle Inspection">
<div id="manufacturing-container">
<h2>
<span>Manufacturing</span><br>
We provide high quality, low cost solutions to meet your requirements.
</h2>
<p>something something something, DarkSide...</p>
</div>
</section>
Working example:
html {scroll-behavior:smooth}
.long {height:100vh; background:#efc}
<a id="ship-it" href="#manufacturing" class="services">
<div id="image-container_4">
<div id="image_4">
<div id="overlay_4"></div>
<h2 class="h2">We pack it and ship it</h2>
<img id=imageB src="https://picsum.photos/50/50" alt="">
</div>
</div>
</a>
<section class="long">Placeholder to enable scroll</section>
<a name="manufacturing"></a>
<section id="manufacturing-section" class="section">
<img src="https://picsum.photos/400/220" alt="Magnetic Particle Inspection">
<div id="manufacturing-container">
<h2>
<span>Manufacturing</span><br>
We provide high quality, low cost solutions to meet your requirements.
</h2>
<p>something something something, DarkSide...</p>
</div>
</section>
Hope it helps.

Putting an html letter into a bootstrap div without breaking styles

Let's say I have this wonderful html email letter. Gist.
And I would like to put it inside an HTML page made with bootstrap. Like this:
<div class='col-md-4'>
<h1>Hello</h1>
</div>
<div class='col-md-8'>
HERE
</div>
If I do it right away, my styles will break. Everything becomes a mess. If I start cutting out styles from the message, it will start losing its colors, font sizes, etc.
Basically, I would like to keep the message intact, but I need the following to be true:
Message keeps its email styles, not overriding outer document styling
Outer document keeps its bootstrap styles
Message fits perfectly into the col-md-8 div, without breaking anything
Is this even possible?

You can either use an iframe or you can use php include.
For the latter, just copy the email body content (content within the <body>....</body>) to a new file and name it say, email.php (Don't worry. There's only one line of php involved).
Then in your current webpage, add a php include line like this:
<div class='col-md-4'>
<h1>Hello</h1>
</div>
<div class='col-md-8'>
<?php include 'email.php';?>
</div>
And then, copy the css in the <style>....</style> to a new file, say `email.css' and link the current webpage (not the email.php) to that css.
N.B. Just make sure to rename your current webpage from someName.html to someName.php and also make sure that your email.php is in the same directory as the main file and you're good to go.
You mentioned that you want the styling of the main webpage and the email webpage to be independent of each other. For that, just wrap your email.php content with a div wrapper like this:
<div id="specialStyle">
<!-- your email content -->
</div>
Now for any elements whose id or class is same on both pages, say:
#commonName { /* <---- This is the main webpage --> */
font-size:14px;
}
#commonName { /* <---- This is the email webpage --> */
font-size:18px;
}
Just add #specialStyle to the email version like this:
#specialStyle #commonName {
font-size:18px;
}

Optimize the loading of my Tumblr with JavaScript to customize styles

--
Hi !
Reader, if you are not comfortable with Tumblr, please tell me, I will give more details!
I had some issues on my tumblr page with the default theme 'Optica'. When I post an embed SoundCloud track, here is what I get on the page:
photo below
NOTE: I have tried to change the theme, and I discovered that for some of them, everything goes fine, but there are a few others with the same bug
So I've tried to fix that, and I've located the origin of the bug in the styles sheet main.css:
.video .video-wrapper {
background: #111;
position: relative;
padding-bottom: 56%;
height: 0;
}
The thing is, that to publish an embed code, you have to do it through the "Video post" tool on your tumblr dashboard, which then allows to style the embed code with the .video-wrapper
Of course, what I want to do here is reducing the bottom padding, but if I do it that way, it will affect all "Video posts". So I used the existing class .soundcloud_audio_player in the iframe to "mark" this type of Video posts to be able to change the styling only of these Video posts.
I have simplified it, and here is what it looks like at the end in browser:
<article class="audio not-page post-70801339374 " data-post-id="post_70801339374">
<div class="post-wrapper clearfix">
<section class="post">
<figure>
<div class="video-wrapper">
<iframe class="soundcloud_audio_player" />
</div>
</figure>
<section class="attribution-tags clearfix">
<ul>
<li>
SoundCloud
</li>
<li>
Blutch
</li>
</ul>
</section>
</section>
<section class="panel" />
</div>
<article>
And now, what I have put between tags in my Tumblr customized HTML:
<script type="text/javascript" src="http://www.google.com/jsapi"></script>
<script type="text/javascript">
google.load("jquery", "1.3");
google.setOnLoadCallback(function() {
jQuery(function($) {
$("iframe.soundcloud_audio_player").parents('div.video-wrapper').css("padding-bottom", "17%");
});
});
</script>
I used jQuery because I didn't know anything about JavaScript or jQuery before today, and I thought it what simpler! But maybe I'm wrong. Anyway, PROBLEM #1 FIXED!
NOW, PROBLEM #2
When the page is loading, the former styling (before than JS intervene) appears for 1 or 2 sec (with my bandwidth anyway!) and it's quite ugly:
photo below
I've looked a bit here
http://www.memodev.com/wiki/Optimiser_un_site_Web
and here
https://developers.google.com/speed/docs/best-practices/rules_intro?hl=fr-FR
But I can't find how to improve the loading, and I hope some of you guys can :)
PageSpeed test below

It sounds like you just want to hide the fact that styles are changing after the page loads -
So, this will do the trick very basically :
Add this to your HTML:
<div id="screen"></div>
Add this to your CSS :
div#screen {
position:fixed;
height:100%; width:100%;
background:white;
z-index:999;
}
You might not need the z-index
There are lots of loaders you can use in place of this, if you would like -
and then,
In JQuery:
$(document).ready(function(){
// Here, you insert that code that adds the padding to your iframe, and whatever else
// you need to do to prepare the page...
$("#screen").hide(); // this will display your page - !
});

Wrap link <a> around <div>

Is it possible to wrap an <a> tag around <div>s like so:
<a href=etc etc>
<div class="layout">
<div class="title">
Video Type
<div class="description">Video description</div>
</div>
</div>
</a>
Eclipse is telling me the div's are in the wrong place?
If this is not allowed. How can I make the entire 'layout' class become a link?

That structure would be valid in HTML5 since in HTML5 anchors can wrap almost any element except for other anchors and form controls. Most browsers nowadays have support for this and will parse the code in the question as valid HTML. The answer below was written in 2011, and may be useful if you're supporting legacy browsers (*cough* Internet Explorer *cough*).
Older browsers without HTML5 parsers (like, say, Firefox 3.6) will still get confused over that, and possibly mess up the DOM structure.
Three options for HTML4 - use all inline elements:
<a href=etc etc>
<span class="layout">
<span class="title">
Video Type
<span class="description">Video description</span>
</span>
</span>
</a>
Then style with display: block
Use JavaScript and :hover:
<div class="layout">
<div class="title">
Video Type
<div class="description">Video description</div>
</div>
</div>
And (assuming jQuery)
$('.layout').click(function(){
// Do something
}):
And
.layout:hover {
// Hover effect
}
Or lastly use absolute positioning to place an a anchor with CSS to cover the whole of .layout
<div class="layout">
<div class="title">
Video Type
<div class="description">Video description</div>
</div>
<a class="more_link" href="somewhere">More information</a>
</div>
And CSS:
.layout {
position: relative;
}
.layout .more_link {
position: absolute;
display: block;
top: 0;
bottom: 0;
left: 0;
right: 0;
text-indent: -9999px;
z-index: 1000;
}
This won't work with older versions of IE, of course.

While the <a> tag is not allowed to contain <div> element, it is allowed to contain other inline elements such as <span>.
When I encountered the problem i swapped the div tag with a <span>. Since the span tag is an inline element, you need to apply a display:block to the css of your <span> element, in order to make it behave like the <div> block element.
This should be valid xhtml and does not require any javascript.
Here's an example:
<a href="#">
<span style="display:block">
Some content. Maybe some other span elements, or images.
</span>
</a>

Another simple solution - just add an onclick event handler to the div thusly:
<div class="layout" onclick="location.href='somewhere'">
<div class="title">
Video Type
<div class="description">Video description</div>
</div>
</div>
This works great for me but there is one small gotcha. I'm not sure how search engine friendly this is. I fear that google's web crawlers might not find this link so I also tend to include a traditional A HREF link somewhere in the block like this:
<div class="layout" onclick="location.href='destination_url'">
<div class="title">
Video Type
<div class="description">Video description</div>
</div>
This is a link
</div>

Timothy's solution is correct ... instead of wrapping an anchor around a div ... you simply give layout to the anchor element with display:block and add the size and width of the anchor ...
.div_class { width: 100px; height: 100px; }
.div_class a { width: 100px; height: 100px; display: block; }
<div class='div_class'></div>

HTML provides two general elements, where div is a natural block element, and span is a natural inline element. All other elements are similarly assigned to be a natural block or inline.
Now, while both can be made by css display to be any of inline, inline-block or block, they are still treated for enclosure purposes as their natural selves, hence the warning messages. Leopards and spots sort of thing.
However, css is only meant to be for making what an element looks like (presentation), but not actually be like (functionality), so it doesn't change an element's basic nature, though that gets very fuzzy in practice. A span made block becomes a bully that kicks everything else off the line, which is very un-inline sort of behaviour.
So, to mitigate against possible conflicts between their natural and css-induced behaviours, it is better to allow:
div or any natural block tag to only ever be block or inline-block.
span or any natural inline tag to only ever be inline or inline-block.
This will also mitigate against tending to build page structures that will likely end up churning out error and warning messages.
Basically, NEVER embed a natural block tag inside a natural inline tag, at any depth.
Why there is a really a distinction is perhaps due to a simplistic idea of what HTML was going to be used for when it was first dreamed up.
Certainly, framework makers got around a lot of these what-to-embed-where problems by just using myriads of divs everywhere, and 'divitis' was born, and still alive and well in every framework. Just have to press F12 in a browser on almost any commercial web page and drill down through a dozen divs. This very page has 15 unbroken levels of divs.
It is not hard to see why just settling on divs made sense. For example, a p tag may have a bunch of links to various sites, and that is ok because inline links are allowed in a block p. However, if not wanting to have query variables visible in those urls, then buttons are required. If only one, then the p can be put inside a form, as a p cannot contain a form.
The formaction attribute on a button can be used to target a url other than the form default, but it still does not allow independent forms, each with their own set of hidden inputs. A button can use the form attribute to use it with a form that isn't an ancestor, but it can get messy to keep track of.
For multiple links to different sites to appear as part of one paragraph though, the only way is to use a div instead of the p and then wrap each button in its own form set to inline. Most frameworks have to cope with so much more complex scenarios that nested divs are the only way to go.
It meant that they really only had to manage one tag per purpose and manage it as if it was an isolated environment. So what was meant to be an occasionally-used functional grouping tag became the web's Lego block. And none of them are going to risk breaking their frameworks by converting to HTML5 semantic tags in a hurry. In the end, semantic tags only really work for fairly static content rather than rich interactive sites.

I had tried to create custom solution using jQuery, which would imitate same behavior as a tag does, for parent DIV.
DEMO:
https://jsfiddle.net/kutec/m9vxhcke/
As per W3C standard, you cannot do this:
<div class="boxes">
<a href="http://link1.com" target="_blank">
<div class="box">
<h3>Link with _blank attr</h3>
</div>
</a>
</div>
You must follow this:
<div class="boxes">
<div class="box">
<h3>
Link with _blank attr
</h3>
</div>
</div>
But by following above code, you wouldn't get the whole DIV clickable :).
Correct structure should be something like this, which also allows you to click over the DIV to redirect on the given href value:
<div class="boxes" data-href="http://link1.com" data-target="_blank">
<div class="box">
<h3>
Link with _blank attr
</h3>
</div>
</div>
Simple Solution:
$(function() {
$('.boxes a').each(function(){
var aTag = $(this).attr('href');
$(this).parent().attr('data-href',aTag);
$("[data-href]").click(function() {
window.location.href = $(this).attr("data-href");
return false;
});
})
}(jQuery));
Dynamic Solution:
(function ( $ ) {
$.fn.dataURL = function() {
// variables
var el = $(this);
var aTag = el.find('a');
var aHref;
var aTarget;
// get & set attributes
aTag.each(function() {
var aHref = $(this).attr('href');
$(this).parent().attr('data-href',this);
aTarget = $(this).attr('target');
$(this).parent().attr('data-target',aTarget);
});
// imitation - default attributes' behavior on "data-" attributes
$(el).delegate('[data-href]','click', function() {
var loc = window.location.href;
loc = $(this).attr("data-href");
aTarget = $(this).attr('data-target');
if(aTarget == "_blank"){
window.open(loc);
} else {
window.location = loc;
}
return false;
});
//removing attributes from selector itself
el.removeAttr('data-href');
el.removeAttr('data-target');
// css
$('[data-href]').css('cursor','pointer');
};
}( jQuery ));
Final call:
<script>
$('.boxes').dataURL();
</script>
Hope this would be helpful :)

You would just want to style the "a" tag as display: block;
Eclipse is appropriately telling you that your HTML is not to spec (as a div tag is not allowed in an anchor tag).
But, since you seem to want to be visually making the anchor look like a big-ol-box, then simply style it as such :)

One easy way to make the div a link/clickable is by using html javascript onclick attribute:
<div class="clickable-div" onclick="location.href='#';"><div> ... </div></div>