This is a question regarding Angular 2 selectors, Custom tags vs. Custom attributes, SEO and browser rendering.
When I first started to look over Angular 2, the very first thing I did when following their quickstart, right of the bat, was to change my selector to '[my-component]' (attribute selector) instead of 'my-component' (tag selector), so I could have <div my-component></div> in my html instead of <my-component></my-component>, which isn't valid html. So I would write html according to standards. Well, at least pretty close to standards (because my-component isn't a valid html attribute, but I could live with only that html validation error)
Then, at some point in a video on youtube, someone from the angular team mentioned that we should use the tag selector, performance wise at least.
Alright I said, screw html validation... or shouldn't I?
So:
Say I ignore the W3C screaming about my html being completely invalid because of the <custom-tags>. I actually have another bigger and more real concern: how does this impact SEO?
I mean don't just think client-side app, because in the real world (and for my angular 2 project as well) I also have server-side rendering, for 2 very important reasons: SEO and Fast initial rendering of the site to the user for that initial view, before the app bootstraps. You can not have a very high traffic SPA otherwise.
Sure, google will crawl my site, regardless of the tags I use, but will it rank it the same in both scenarios: one with <custom-make-believe-tags> and the other with only standard html tags?
Let's talk browsers and css:
As I started to build my first SPA site in Angular 2, I was immediately faced with another concern:
Say (in a non SPA site) I have the following html markup:
<header>
<a class="logo">
...
</a>
<div class="widgets">
<form class="frm-quicksearch"> ... </form>
<div class="dropdown">
<!-- a user dropdown menu here -->
</div>
</div>
</header>
<div class="video-listing">
<div class="video-item"> ... </div>
<div class="video-item"> ... </div>
...
</div>
Angular 2 wise I would have the following component tree:
<header-component>
<logo-component></logo-component>
<widgets-component>
<quicksearch-component></quicksearch-component>
<dropdown-component></dropdown-component>
</widgets-component>
</header-component>
<video-listing-component>
<video-item-component></video-item-component>
...
</video-listing-component>
Now, I have 2 options. Let's just take the <video-listing-component> for example, to keep this simple... I either
A) place the entire standard html tags which I already have (<div class="video-item"></div>) within the <video-item-component> tag, and once rendered will result in this:
<video-listing-component>
<div class="video-listing>
<video-item-component>
<div class="video-item>...</div>
</video-item-component>
...
...
</div>
</video-listing-component>
OR:
B) Only put the content of <div class="video-item"> directly into my <video-item-component> component and adding the required class (class="video-item") for styling on the component tag, resulting in something like this:
<video-listing-component class="video-listing">
<video-item-component class="video-item"></video-item-component>
<video-item-component class="video-item"></video-item-component>
...
</video-listing-component>
Either way (A or B), the browser renders everything just fine.
BUT if you take a closer look (after everything is rendered in the dom, of course), by default the custom tags don't occupy any space in the dom. They're 0px by 0px. Only their content occupies space. I don't get it how come the browser still renders everything as you would want to see it, I mean in the first case (A):
While having float: left; width: 25%; on the div class="video-item", but each of these divs being within a <video-item-component> tag, which doesn't have any styling... Isn't it just a fortunate side-effect that the browser renders everything as you'd expect? With all the <div class="video-item"> floating next to eachother, even though each of them are within another tag, the <video-item-component> which does NOT have float: left? I've tested on IE10+, Firefox, Chrome, all fine. Is it just fortunate or is there a solid explanation for this and we can safely rely for this kind of markup to be rendered as we'd expect by all (or at least most) browsers?
Second case (B):
If we use classes and styling directly on the custom tags (<video-item-component>)... again, everything shows up fine. But as far as I know, we shouldn't style custom components, right? Isn't this also just a fortunate expected outcome? Or is this fine also? I don't know, maybe I'm still living in 2009... am I?
Which of these 2 approaches (A or B) would be the recommended one? Or are both just fine?
I have no ideea!!
EDIT:
D'oh, thanks Günter Zöchbauer. Yeah, since my divs have float: left, that's why the (custom or not) tag they're wrapped in doesn't expand it's height. Seems I've forgotten how css works since I started to look over Angular 2:)
But one thing still remains:
If I set a percentage width on a block element (call it E), I would assume it takes x% of it's immediate parent. If I set float: left, I would expect floating within the immediate parent. In my A case, since the immediate parent is a custom tag with no display type and no width, I would expect for things to break somehow, but still... my E elements behave like their parent isn't the custom tag they're each wrapped in, but the next one in the dom (which is <div class="video-listing> in my case). And they occupy x% of that and they float within that. I don't expect this to be normal, I would think this is just a fortunate effect, and I'm afraid that one day, after some browser update... I'll wake up to find all my Angular 2 sites looking completely broken.
So... are both A and B an equally proper approach? Or am I doing it wrong in case A?
EDIT2:
Let's simplify things a bit. As I got part of my question answered, let's take another example of generated html (simplified a bit, with inlined css):
<footer>
<angular-component-left>
<div style="float: left; width: 50%;">
DIV CONTENT
</div>
</angular-component-left>
<angular-component-right>
<div style="float: left; width: 50%;">
DIV CONTENT
</div>
</angular-component-right>
</footer>
In the original, not yet implemented html (whithout <angular-component-...>, those divs should float left and each occupy 50% of the <footer>. Surprisingly, once they're wrapped in the <angular-component-...> custom tags, they do the same: occupy 50% of the footer. But this just seems like good fortune to me, dumb luck... Unintended effect.
So, is it or isn't it "dumb luck"?
Should I leave it like that, or rewrite so instead of the above code, I would have something like this:
<footer>
<angular-component-left style="display: block; float: left; width: 50%;">
DIV CONTENT
</angular-component-left>
<angular-component-right style="display: block; float: left; width: 50%;">
DIV CONTENT
</angular-component-right>
</footer>
Note that the inline styling is introduced here for simplicity, I would actually have a class instead which would be in an external css file included in the <head> of my document, not through style or styleUrls from my angular components.
The issue is your HTML validator. The - in the element name is required for elements to be treated as custom elements and it is valid HTML5. Angular doesn't require - in element names but it's good practice.
Check for example https://www.w3.org/TR/custom-elements/#registering-custom-elements (search for x-foo) or https://w3c.github.io/webcomponents/spec/custom/#custom-elements-custom-tag-example. I'm sure this dash rule is specified somewhere but wasn't able to find the spec. It is for example required in Polymer that depends on elements being proper custom elements while this doesn't matter much in Angular. The only difference as far as I know is that when you query the element, you get a HTMLUnknownElement when the - is missing in the name and a HTMLElement when it contains a -.
See also this question I asked a few years ago Why does Angular not need a dash in component name
BUT if you take a closer look, by default the custom tags don't occupy any space in the dom. They're 0px by 0px. Only their content occupies space. I just don't get it how come the browser still renders everything as you would want to see it
I'm not sure I understand this question. When Angular processes the template it adds the content dynamically. When you see the content in the browser than it's also available in the DOM and has actual dimensions.
Search engine crawlers are able to process pages that are generated by JavaScript. If this isn't enough, server-side rendered pages can provide static HTML to crawlers that contain the whole view.
I'm working on a facebook tab that includes an iframe showing content from another website. I've narrowed the iframe down to only showing the part of the website that I want it to and disabled scrolling. In addition to that, I'd like to disable the links in the iframe content, and I've read that it should be possible by adding a transparent .png background image to a div containing the iframe and setting the iframe's z-index to -1, but the iframe is still in front of the image.
So far my css looks like this:
<style type="text/css">
iframe
{
z-index:-1;
}
.bgimg {
background-image: url('transparent.png');
}
</style>
and my html like this:
<div class="bgimg" style="overflow:hidden; width: 700px; height: 100%;margin:auto;">
<iframe src="http://www.url.com/site.html" width="1100" height="700" seamless="seamless" frameborder="0" scrolling="no" style="margin-top:-230px;"></iframe>
</div>
I'm using this to give a direct link to my amateur soccer team's league table, instead of manually having to update the tab each week with all the new information, but I don't want it to be possible to click on each team for team information - just the League table.
I've read several places that this should be possible, but haven't been able to find a functioning code - also read a few places saying it's impossible, and yet some others that say it can only be done using jQuery (which I know nothing about).
If anyone has any alternative solutions to what I'm doing now - please let me know.
Keep in mind that z-index only works for positioned elements (can be relative though.)
See: http://www.w3.org/TR/CSS21/visuren.html#z-index:
Applies to: positioned elements
On Wordpress i'm using youtube channel list plugin.
It works well, but the align of the videos don't looks great. Actually display diagonal list below the BIG video!
Can someone suggest me how to fix this issue with css?
here's the page
http://www.snowypeach.com/home/?page_id=1106
I need the list under the video aligned horizontal, not diagonal!
You have nested a <div /> as a child of the <ul />. This is invalid markup. Move the <li/> elements to be the children of the <ul />, delete the <div /> and it will work
EDIT
Okay I see the problem. You are wrapping all this content within a <pre/> tag. This tag shouldn't be used here but if you are unable to get rid of it add the style white-space: normal;.
I tested the previous answer by moving elements within chrome dev tools which removed the whitespace and therefore the problem.
Hope this helps :)
There is class ytc-columns4 on the below <ul> which is taking control over the alignment of the small video <li> tags
<ul class="ytchagallery ytccf ytc-table ytc-td-bottom ytc-columns4">
according to that class the below css is generating by plugin in the css file on line 66
http://www.snowypeach.com/home/wp-content/plugins/youtube-channel-gallery/styles.css?ver=3.4.1
.ytc-columns4 li {
width: calc(100% / 4 + 10px / 3);
}
i have changed the class ytc-columns3 and ytc-columns2 and result vary every time. I am not exactly getting where is the calculation part of the plugin. Other wise i can tweek the code.
Here's what I've got. I have a tree in GWT set up to process only a certain level depth of children, retrieving from the server and only updating according to which children one clicks. I am familiar with addStyleName() functions and I have used this to style the foreground color of certain tree nodes, and it has appeared successfully on previous versions of my project (without the server calls).
The question boils down to if any of you familiar with GWT know any reason why my custom CSS would be overridden on a child update of a node. So for example, when the server processes a node, it shows up in my proper CSS color, but once the server shows that it has children, it does the addItem() to that node and the CSS of the text color of the parent is reverted back to default.
This is all under the assumption that I have no removeStyleName() calls or any deleting/recreating going on. Anyone familiar with a situation like this?
Thanks!
EDIT: Here's some code I've narrowed it down to
HTML
<html>
<head>
<link type="text/css" rel="stylesheet" href="test.css">
</head>
<body>
<p>blaghblagh</p>
<div class="Foreground1">
hey
<table style="white-space: nowrap;">
<tbody>
<td style="vertical-align: middle;">
<div style="display: inline;">
ContinuingPromise '08
</div>
</td>
</tbody>
</table>
CSS:
body{
color: black;
}
.Foreground1{
color: green;
}
If you put this code up, you'll see the ContinuingPromise as black, although it is within the foreground div which should be green. Also, the word 'hey' will appear green. Am I missing something basic? Thanks again
I'm not sure if this solved your original question, but the color problem is very likely caused by the doctype you're using. If the html page uses quirks mode, the style properties are not correctly inherited by the table. See http://reference.sitepoint.com/css/inheritance. Setting a doctype or different doctype might solve your problem. If you are using any of the GWT layout panels you need to set the doctype to <!DOCTYPE html>, see http://code.google.com/webtoolkit/doc/latest/DevGuideUiPanels.html#Standards
Take a look at this page in FireFox. Feel free to navigate to any of the top six product categories to see more of the same type of code.
If you are [un]lucky enough to see the glitch, you will see at least one product box expand it's height to epic proportions.
Here is the code:
<div class="product_category">
<a href="../products/dht_1500.php" style="height: 340px;">
<h3>DHT 1500</h3>
(superfluous HTML omitted here)
</a>
</div>
Here is what Firebug reveals:
<div class="product_category">
<a style="height: 340px;" href="../products/dht_1500.php"> </a>
<h3><a _moz-rs-heading="" style="height: 340px;" href="../products/dht_1500.php">DHT 1500</a></h3>
(superfluous HTML omitted here)
<a style="height: 340px;" href="../products/dht_1500.php"> </a>
</div>
You can see FireFox is definitely closing my tags and re-opening them again, and pulling the custom CSS height style along with it, which is resulting in each product box height skyrocketing. Also note that strange _moz-rs-heading="" bit.
I suspect my problem has to do with my using block HTML elements within an inline tag, but I thought I solved that problem by converting the tags to block formatting in my stylesheet:
.product_category a {
display: block;
}
FireFox is playing favorites to my tags. It usually renders the page like I want it, but then every once-in-a-while, it will blow one of my product boxes sky-high, and seemingly at random.
The pages work properly in Internet Explorer and Safari. I have been testing it with FireFox 3.6 on Mac, but have seen the same problem on FireFox for PC.
Having block level elements (h3) inside an inline element (a) is not valid HTML.
Change your block elements to a span and use CSS to style it how you wish.
A similar question with the exact same symptoms was asked a few days back. The solution there was in fact taking the native block elements out of the natively inline ones. Seems changing display doesn't help in this case.