angular4:ng-content nested class based selection - javascript

As we all know in Angular4 we have support for ng-content.
In this, we can select based upon class, element-name, attributes.
I am trying to select element based upon class :
Here is my consumer component html :
<my-component>
<div class = "item">
<div class = "item-small">small-item content</div>
<div class = "item-large">large-item content</div>
</div>
</my-component>
Now in my my-component template, I am trying to access div with class item-small.
My my-component template looks as follows:
<div class="my-component">
<ng-content select = ".item>.item-small"></ng-content>
</div>
But it is not returning me anything.
Here is the plunk for this issue:
https://plnkr.co/edit/2hlL2GezNXRoLCD1FAPD?p=preview
What is the best option to handle such cases?
Kindly give right approach to solve this problem.

I'm pretty sure only selectors are supported that directly match elements
This should work
".item-small"
but this not
".item>.item-small"
like with element or directive selectors.

Related

How to render a content inside directive at various places

I want a component directive to render anything put inside it's selector to be rendered at specific sections inside its html.
header, footer, main in this case.
any.html
<any-selector>
<div>content to place</div>
</any-selector>
Expecting it to render following
any-selector.html
<header><div>content to place</div></header>
<main><div>content to place</div></main>
<footer><div>content to place</div></footer>
tried it with ng-content but it rendered only at first occurrence of <ng-content>
If there's any way to achieve this?
So, this is an expected behavior from ng-content, either you put [select] to point to certain ng-content or you can render just on the first occurrence of ng-content.
I tried a way which has worked for me. Here is the demo working code
<any-selector>
<div #myProjection>content to place</div>
</any-selector>
and then in app-selector.HTML you can do :
<div id='border'>
<h1>Hello Component</h1>
<header><div #canvas></div></header>
<footer><div #canvas></div></footer>
</div>
app-selector.component
#ViewChildren("canvas") canvas: QueryList<ElementRef>;
#ContentChild("myProjection") str : ElementRef;
ngAfterViewInit() {
this.canvas.forEach((div: ElementRef) =>
div.nativeElement.insertAdjacentHTML('beforeend', this.str.nativeElement.innerHTML));
}

ng component not useful

I was learning the ng-content. Why need to use it when we can easily write like this
with ng-content
menu.component.html
<div>
<app-message> <h1>Laptop</h1></app-message>
</div>
message.component.html
<div>
<ng-content></ng-content>
<p>something text to be display</p>
<button > Submit</button>
</div>
without ng-content
menu.component.html
<div>
<h1>Laptop</h1>
<app-message> </app-message>
</div>
message.component.html
<div>
<p>something text to be display</p>
<button > Submit</button>
</div>
Using <ng-content> allows you to create flexible reusable components.
For example, a custom app-modal component:
<div class="modal">
<div class="modal-title">
{{title}}
</div>
<div class="modal-body">
<ng-content></ng-content>
</div>
</div>
This is very powerful, and only the start of what you can achieve with <ng-content>
A core prinpiple of software engineering is code reuse (DRY). With this we can bundle all of the logic relating to a component into one component, and inject the content into it.
This is like asking the question
Why not just declare your CSS styles inline instead of in CSS classes?
It is possible, but unmaintainable, and we have evolved beyond that.
Your example is fairly trivial, but it is still useful if you wanted to change style or behaviour based on some injected logic.
There exist some situations when is necessary, maybe no in simple cases but when the app grows up and you have to insert a custom component inside another is very usefully
As you can see from your own example, without using ng-content, the parent component suddenly is partially responsible for the child's layout. It'll get messy real quick, the quicker the more complex the layout gets.
It's useful for displaying components inside of other components, so the components can be reusable. For example, if you want to display some text on a few pages, you call the component with the text inside of the other components that you want the text to be displayed on. It could also be useful for showing different information but styled in the same format. E.g.
if your ng-content already has the information this is an example of how it would be used:
menu.component.html
<ng-content></ng-content>
message.component.html
<ng-content></ng-content>
This is good because you can copy and paste the exact component into another one without having to rewrite the code
If your ng-content is looking for a data source for information to pass into it
<ng-content [data]='data'></ng-content>
This is good because you can recreate the component inside of another component but with different data inside of it.
If you've ever used react, you pass data into it in a similar way here as you would with react props, but instead of props in angular, it will be an #input field. Here is some example code
test.component.html
<ng-content [data]='THIS IS THE DATA'></ng-content>
This is the actual component, as you can see, it is looking for a data source
ng-content.component.html
<p>The data we are looking for is {{data}} </p>
ng-content.component.ts - this says that when the component is called, it is looking for an input called 'data' and the type has to be a string
#Input() data: string;
We would then see the test.component.html displayed like this:
The data we are looking for is THIS IS THE DATA

How to select content from inner children in ng-content

I have a component called tab which has <ng-content select="[tabItem]"></ng-content>
Sometimes tabItem is inside other child components. My problem is Angular selects the content from direct children, not inner children (app-my-tab), is there any way to do it?
app.component.html
<app-tabs>
<div tabItem>
Tab 1
</div>
<div tabItem>
Tab 2
</div>
<app-my-tab></app-my-tab>
</app-tabs>
my-tab.component.html
<div tabItem>
My Tab
</div>
<div>
Other content
</div>
See this stackblitz
There is no solution for deep selection.
I thing it is logical, because:
understand and real code easily
easy to debug.
If you want really do that use *ngIf in app-my-tab.
To use *ngIF:
All element in app-tabs must have tabItem attribute
send your condition to show/hide some other element in to app-my-tab component. and app-my-tab receive it as #Input() property
in app-my-tab html use *ngIf to show or hide some element
Example: https://stackblitz.com/edit/deep-ng-content-2gyttv?file=src/app/app.component.html

using document.querySelector with complex CSS selectors

In JavaScript I want to use document.querySelector to "grab" the last div (<div class="widget-footer">) in below HTML. However after many tries, I still can't figure out the correct CSS selector syntax to use.
The following code does not work:
document.querySelector (".skin-grid-widgets.ui-sortable.gridWidgetTemplatePositie.AgendaStandaard.disablesorting.hoogte-1-knoppen-0.breedte-1.widget-footer")
Here is the HTML I am working with
<div class="skin-grid enkeleKolom" id="Infobalk">
<div class="skin-grid-widgets ui-sortable">
<div class="gridWidgetTemplatePositie AgendaStandaard disablesorting hoogte-1-knoppen-0 breedte-1">
<div class="widget-header">
here comes the header text
</div>
<div class="widget-body">
some body text
</div>
<div class="widget-footer">
here comes the footer text
</div>
</div>
</div>
</div>
I've surfed everywhere to find example of complex CSS selectors used with querySelector, but to no avail. Any help would be really appreciated.
Your issue is you need a space in between each child element you are trying to select. If you do not have spaces in between your class selectors, by CSS specification, it will look for both classes on the same element.
Change your selector to look like the following:
var footer = document.querySelector(".skin-grid-widgets.ui-sortable .gridWidgetTemplatePositie.AgendaStandaard.disablesorting.hoogte-1-knoppen-0.breedte-1 .widget-footer");
footer.classList.add("highlight");
.highlight {
background-color: yellow;
}
<div class="skin-grid enkeleKolom" id="Infobalk">
<div class="skin-grid-widgets ui-sortable">
<div class="gridWidgetTemplatePositie AgendaStandaard disablesorting hoogte-1-knoppen-0 breedte-1">
<div class="widget-header">
here comes the header text
</div>
<div class="widget-body">
some body text
</div>
<div class="widget-footer">
here comes the footer text
</div>
</div>
</div>
</div>
try this:
<script>
document.querySelector (".skin-grid-widgets .gridWidgetTemplatePositie .widget-footer");
</script>
You don't need to add adjacent classes like "skin-grid-widgets ui-sortable" in querySelector, if you do so then query selector assumes that "skin-grid-widgets" is parent of "ui-sortable". Use just one of the classes at one DOM level.
The selector ain't complex, your thoughts are.
Listen to yourself, to the description you provide of what you want to select:
"grab" the last div in below HTML
Not grab the node with the class widget-footer inside of a node that has all these classes: gridWidgetTemplatePositie AgendaStandaard disablesorting hoogte-1-knoppen-0 breedte-1, inside a node ...
//a utility, because DRY.
//and because it's nicer to work with Arrays than with NodeLists or HTMLCollections.
function $$(selector, ctx=document){
return Array.from(ctx.querySelectorAll(selector));
}
//and the last div in this document:
var target = $$('div').pop();
or
"grab" <div class="widget-footer"> in below HTML
var target = document.querySelector("div.widget-footer");
or the combination: grab the last div.widget-footer in the HTML
var target = $$('div.widget-footer').pop();

How to expand DIVs the "angular way" (using angular masonry)

I'm trying to expand a DIV element on my angular layout. I'm using angular-masonry to give a mason-style to my layout, but now I need to expand those boxes on click. I've tried a lot of stuff, but it kept overlapping my others elements. Soon figured out that I'll have to write it the "angular way" so I don't run into DOM manipulation conflicts.
Here's my code:
<div class="row" masonry>
<div
class="masonry-brick item-component col-sm-4 col-md-4"
ng-repeat="component in components.components | filter : components.filterByFilter | filter : searchText"
ng-click=" // expand #expandable // "
>
<div class="component-wrapper">
<div class="component">
<img ng-src="#{{ component.thumb }}"/>
</div>
<div class="component">
#{{ component.name_en }}
</div>
</div>
<div id="expandable" class="expand-me codes-wrapper">
<p>XXX</p>
<p>YYY</p>
<p>ZZZ</p>
</div>
</div>
</div>
Here's what I want to accomplish in the "angular way": http://codepen.io/desandro/pen/daKBo
In your example (http://codepen.io/desandro/pen/daKBo) if you click on an element there are two things that will be done:
(1) the style of the clicked item is changed
(2) the function masonry is called on the container element that keeps the divs.
I can't see such a function in angular-masonry pre builded. So i'll guess you have to do this by your self. Here are some hints how to solve this (i havn't try it in real)
Bind a function to ng-click. In this function set a state to the current component. This state shoud be used to toggle the css-class of the element. you can use ng-class for this.
The second part is little bit more complex. I would suggest write a direcive 'masonry-change-listener' and bind it to the element that is bound to the same element with the directive masonry. If you click on a component $emit an event, that something has changed. In the directive 'masonry-change-listener' listen to this event. if this event fires you have to call $element.masonry.apply($element) in the link function.

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