When using element directives I have seen Angular element directives used in two ways:
1. As block level components
The element is styled as display:block, is the component and its children are the component's children, so the element itself is the component.
Use of directive:
<example class="Example"></example>
The directive's html:
<header class="Example-header"></header>
<img class="Example-image">
<footer class="Example-footer"></footer>
2. As an inline wrapper of the component
The element is left as display:inline and effectively acts as an invisible wrapper for the component itself:
Use of directive:
<example></example>
The directive's html:
<div class="Example">
<header class="Example-header"></header>
<img class="Example-image">
<footer class="Example-footer"></footer>
</div>
Obviously each have advantages and disadvantages for example extra markup, loss of layout context due to inline element etc, but is one the correct way? or is this another of Angular's vagaries?
I'm surprised no one responded, but the idea behind creating custom directives is the ability to create reusable pieces of code that fulfill a specific bit of functionality on your site.
This functionality, however, doesn't care about the styles that you are going to use. You can of course conditionally change classes and styles from within Angular, but the core component when dealing with the framework is the data.
With that being said, there is no "correct way" as you bolded in your question. Develop the directive to fit your needs and style of your site.
First this is probably opinion based but i'd really like to share my point of view about this.
If you really follow angular way of doing directives none of theses are a correct way.
Directives are intended to add a behavior to an HTML element.
The less the directive add HTML the best it is as it allow you to have a better control on this element.
Lets take an exemple.
We have a data grid (let say ui-grid, it doesn't really matter)
<ui-grid ...>
...
</ui-grid>
I had a the idea to add some button to add or remove element in the grid.
I first came up with this
<ui-grid ...>
...
</ui-grid>
<button ng-click="addItem()">Add</button>
<button ng-click="removeItem()">Remove</button>
I'm really happy with this and that's ok, but finally i need to use theses buttons in some other views. I'll have to duplicate the HTML, duplicate the JS and adapt it to the collection.
The common mistake
That's obviously not a good idea.
Instead i will do a directive. Lets say "button-list" : it produce the same html and behavior.
<ui-grid ...>
...
</ui-grid>
<button-list></button-list>
That's pretty cool.
Now i have some need. On one view i need the add button to be blue, on an other one i don't need to have a remove button, and on a last one i want the button text to be "X" and "+" (That's was some request by a client in a true story).
I could make a big object with a list of option and etc... but this is really painful and you need to touch the directive each time you need to add a custom different little behavior.
The good way to go
Now lets just think again about what i wanted to do.
I want the button to interact with the grid... and that's pretty much all. This is how we should go building a custom directive.
We could then produce this directive this way :
<div grid-button-container collection="mycollection">
<ui-grid ...>
...
</ui-grid>
<button grid-add-item>Add</button>
<button grid-remove-item>Remove</button>
</div>
So what do we have here ? We have three different directives.
grid-button-container : Its responsibility is to hold the list for the sub-directives.
grid-add-item : It add a function on click that add an element to the collection of grid-button-container.
grid-remove-item : It add a function on click that remove an element to the collection of grid-button-container.
Both grid-add-item and grid-remove-item will be requiring the grid-button-container to be used.
I cannot describe all the implementation of this (it would take too long) but i think this is how directives should be used. Such as almost no angular build-in directives (ng-*) add HTML and just add a behavior i think all the directives should be build in this way.
Pro :
You have a full control about your HTML
Directives are tiny and trivial
This is really re-usable
Cons :
Can be harder and longer to implement.
To make a final point, the two way you're asking about are just different. No one is better than the other it will just depend on your own HTML organisation and it will depend on the directive use.
Hope it helped.
Related
Trying to determine the correct syntax for using Microdata inside my breadcumbs implementation. Everything I have read seems to lean towards the fact that the breadcrumbs are structured inside an ordered or unorderd list. Mine is not.
<body itemscope="" itemtype="http://schema.org/WebPage">
...
<div class="breadcrumbs" itemprop="breadcrumb">
Home
<span class="delimiter"> > </span>
Parent Item
<span class="delimiter"> > </span>
<span>Child</span>
</div>
...
</body>
If I run it inside Google's tool it seems correct, but compared to their example it is missing a lot of elements and doesn't have the structure of their example BreadcrumbList.
I'm also a little confused about the correct properties for the links. Should they all have title and url properties?
I was looking at the examples at the bottom of the page here: http://schema.org/WebPage
The breadcrumb property expects one of two values:
Text
BreadcrumbList
If you provide a Text value (like you do in the example), you can’t provide data about each link. If you are fine with that, the Microdata in your example is correct (but it also contains RDFa, which doesn’t seem to make sense, at least not without further context; so if you didn’t add them intentionally, you might want to remove the property attributes).
If you want to provide data about each link, you have to provide a BreadcrumbList value.
For the Microdata, it doesn’t matter whether or not you use a list. If the example uses ol→li→a→span, you could as well use something like div→span→a→span. You just have to make sure to use the correct element type.
If you can’t add parent elements to the a elements, it’s still possible to use BreadcrumbList. But then you would have to duplicate the URL with a link element inside the a element.
I'm reading some code and there is a piece of html that reads:
<div id="uniqueId1234" data-target=".uniqueId1234">
...
</div>
and then earlier on in the same html file there is a span element that seems to use this div as a class:
<span class="uniqueId1234">
...
</span>
Can someone explain how this works? I thought that a class was something created in a css file. Sorry if this is a dumb question.
This is likely part of some piece of Javascript code or a library that listens for some type of change or event on your element with the data-target attribute.
When this event is triggered, it can then use the value of that attribute as a selector for performing some other logic as seen in this basic jQuery-based example below:
// When an element containing your data-target attribute is clicked
$('[data-target]').click(function(){
// Find the appropriate target (i.e. ".uniqueId1234")
var target = $(this).data('target');
// Then use it as a selector for some type of operation
$(target).toggle();
});
Classes are very common within CSS to style multiple elements, but they can also commonly be used as a mechanism in Javascript as well, which is likely the case in your scenario here.
What does it mean to set data-target attribute of a div to the id of that div?
Nothing standard. data-* attributes are designed to hold custom data for custom code (typically client side JS) to process.
I thought that a class was something created in a css file.
Classes are an HTML feature used to put elements into arbitrary groups. They are commonly used when writing CSS, but also client side JS and other code.
I'm recently starting to explore AngularJS, and of course, i know it is ran at the client side, and since SPA (Single Page Applications) are becoming more and more common, i have a question regarding how to safely hide HTML elements.
Let me give a simple example:
Employee
<div ng-show="canSeeSalary">
{{salary}}
</div>
Now, of course, at runtime the div tag related to the salary won't be displayed, however by seeing the HTML source code, or using a developer tool like the one we have in Chrome, it would be possible to see the tag and probably its value.
I know tags like these should be filtered at the the server-side, of course, but since it has come to the client side, the div will be there.
My question is exactly, if there is any way i could hide these divs from the HTML source code, without needing to mix AngularJS with JSTL, for example.
Thanks in advance.
Try ng-if directive:
<div ng-if="canSeeSalary">
{{salary}}
</div>
Corresponding div element will be removed from the DOM. From the official documentation:
The ngIf directive removes or recreates a portion of the DOM tree
based on an {expression}. If the expression assigned to ngIf evaluates
to a false value then the element is removed from the DOM, otherwise a
clone of the element is reinserted into the DOM.
Use
Employee
<div ng-if="canSeeSalary">
{{salary}}
</div>
ng-if completely removes and recreates the element in the DOM rather than changing its visibility via the display css property
I would recommend using ngCloak rather than ngIf.
The ngCloak directive is used to prevent the Angular html template from being briefly displayed by the browser in its raw (uncompiled) form while your application is loading. Use this directive to avoid the undesirable flicker effect caused by the html template display.
example:
<div ng-cloak> {{::test}} </div>
ngCloak # Official Angular Docs
Newbie to ASP.net MVC 4 and trying to make sense of Razor. If I wanted to just display some text in my .cshtml page, can I use
<label class="LabelCSSTop">Introduction</label>
or should I use:
#Html.Label("STW", htmlAttributes: new { #class = "LabelCSSTop" })
Not sure if one is preferred over the other or if either is okay. If the latter emits the label tag anyway, should I just stick to the former?
Again, if I just wanted to display a text box, can I just do this:
<input id="txtName" type="text" />
or should I do this:
#Html.TextBox("txtName", "")
Is there a situation when I should use the #Html over the regular html tag?
Thanks in advance!!
In the case of your label snippet, it doesn't really matter. I would go for the simpler syntax (plain HTML).
Most helper methods also don't allow you to surround another element. This can be a consideration when choosing to use/not use one.
Strongly-Typed Equivalents
However, it's worth noting that what you use the #Html.[Element]For<T>() methods that you gain important features. Note the "For" at the end of the method name.
Example:
#Html.TextBoxFor( o => o.FirstName )
This will handle ID/Name creation based on object hierarchy (which is critical for model binding). It will also add unobtrusive validation attributes. These methods take an Expression as an argument which refers to a property within the model. The metadata of this property is obtained by the MVC framework, and as such it "knows" more about the property than its string-argument counterpart.
It also allows you to deal with UI code in a strongly-typed fashion. Visual Studio will highlight syntax errors, whereas it cannot do so with a string. Views can also be optionally compiled along with the solution, allowing for additional compile-time checks.
Other Considerations
Occasionally a HTML helper method will also perform additional tasks which are useful, such as Html.Checkbox and Html.CheckboxFor which also create a hidden field to go along with the checkbox. Another example are the URL-related methods (such as for a hyperlink) which are route-aware.
<!-- bad -->
my link
<!-- good -->
#Html.ActionLink( "my link", "foo", "bar", new{ id=123 } )
<!-- also fine (perhaps you want to wrap something with the anchor) -->
<span>my link</span>
There is a slight performance benefit to using plain HTML versus code which must be executed whenever the view is rendered, although this should not be the deciding factor.
Depends on what your are doing.
If you have SPA (Single-Page Application) the you can use:
<input id="txtName" type="text" />
Otherwise using Html helpers is recommended, to get your controls bound with your model.
If you want to just display some text in your .cshtml page, I do not recommend #Html.Label and also not to use the html label as well. The element represents a caption in a user interface. and you'll see that in the case of #Html.Label, a for attribute is added, referring to the id of a, possibly non-existent, element. The value of this attribute is the value of the model field, in which non-alphanumerics are replaced by underscores.
You should use #Html.Display or #Html.DisplayFor, possibly wrapped in some plain html elements line span or p.
The helpers are there mainly to help you display labels, form inputs, etc for the strongly typed properties of your model. By using the helpers and Visual Studio Intellisense, you can greatly reduce the number of typos that you could make when generating a web page.
With that said, you can continue to create your elements manually for both properties of your view model or items that you want to display that are not part of your view model.
When it comes to labels, I would say it's up to you what you prefer. Some examples when it can be useful with HTML helper tags are, for instance
When dealing with hyperlinks, since the HTML helper simplifies routing
When you bind to your model, using #Html.LabelFor, #Html.TextBoxFor, etc
When you use the #Html.EditorFor, as you can assign specific behavior och looks in a editor view
#html.label and #html.textbox are use when you want bind it to your model in a easy way...which cannot be achieve by input etc. in one line
Trying to learn html/css. I've been looking at the html & css files of a couple different websites that have something along the line of:
<span class="mytest anothertest">some text goes here</span>
I understand the "mytest" part but what does "anothertest" do? There's no reference to that anywhere in their css or html files.
anothertest is just another class like mytest. You can apply more than one to an element.
There are several possible reasons for the presence of a class name in a class attribute value. Using the class in page stylesheets is probably most widely known, but not the only one:
The class name can be used in JavaScript in order to process a set of elements conveniently. (Using document.getElementsByClass is one way to achieve this; another way is to use jQuery; and you could even hand-code it rather simply.)
Designated class names are used in some metadata systems, such as microformats. Some search engines recognize such names and use them to provide semantic searching (though this approach probably loses to microdata, which uses different attributes).
A class name can be used in a user style sheet, e.g. by a developer who wishes to do some testing. This could well be the case if the class name is literally “anothertest.”
The name might be there to allow future development, e.g. so that elements of a class will be or may be styled in some future version. The designers might have ideas on styling but they haven’t decided on it—they just want it to be easy when they are ready.
It could be just a holdover. It was a class that had some use, but things changed. There was really no particular reason to remove it.
This is a very good question. It involved the difference between id and class.
ID
An ID placed on an element, is a unique identifier for that element. An element may only have one ID, and only one of the same ID may exist on a page. So for instance, the following examples are not possible.
<a id="someid anotherid">Multiple IDs - Wrong</a>
<a id="someid"><span id="someid">Same ID twice - Wrong</span></a>
Class
A class name however, is the exact opposite. An element may have several class names, and the same class name may appear multiple times on a page. Like so:
<a class="someclass anotherclass">Multiple Classes - Correct</a>
<a class="someclass"><span class="someclass">Same Class twice - correct</span></a>
In short, the syntax displayed in the question is simply having 2 class names on one element, which is perfectly acceptable.
Class name are also used to easily select elements in the page with JavaScript. You can use the getElementsByClassName method to access them or using your favorite CSS selector library (ex.: Sizzle) if you need compatibility for older browser.