How to create custom directives in angular 6

How do I create a custom directive in angular 6?

To create a custom directive we have to replace @Component decorator with @Directive decorator. So, let’s get started with creating our first Custom Attribute directive. In this directive, we are going to highlight the selected DOM element by setting an element’s background color. Create an app-highlight.

How can we create a custom directive in angular?

Creating a custom directive is easy. Just create a new class and decorate it with the @Directive decorator. We need to make sure that the directive is declared in the corresponding (app-) module before we can use it. If you are using the angular-cli this should be done automatically.

How do I create a custom directive in angular 10?

How to Create Custom Directive in Angular 10?
  1. Step 1: Create New App.
  2. Step 2: Create Custom Directive.
  3. src/app/btn.directive.ts.
  4. Step 3: Import Module to module.ts file.
  5. src/app/app.module.ts.
  6. Step 4: Update Component HTML File.
  7. src/app/app.component.html.
  8. Output:

What is Dom in angular?

DOM stands for Document Object Model. AngularJS’s directives are used to bind application data to the attributes of HTML DOM elements. The directives are –

What is HostListener in angular?


Decorator that declares a DOM event to listen for, and provides a handler method to run when that event occurs.

What are HostBinding () and HostListener () in angular?

@HostBinding and @HostListener are two decorators in Angular that can be really useful in custom directives. @HostBinding lets you set properties on the element or component that hosts the directive, and @HostListener lets you listen for events on the host element or component.

What is HostBinding angular?


Decorator that marks a DOM property as a host-binding property and supplies configuration metadata. Angular automatically checks host property bindings during change detection, and if a binding changes it updates the host element of the directive.

What is @ViewChild in angular?

The @ViewChild decorator allows us to inject into a component class references to elements used inside its template, that’s what we should use it for. Using @ViewChild we can easily inject components, directives or plain DOM elements.

What is the difference between ViewChild and ContentChild?

ViewChild is used to select an element from component’s template while ContentChild is used to select projected content.

What is @input in angular?

A common pattern in Angular is sharing data between a parent component and one or more child components. @Input() allows a parent component to update data in the child component. Conversely, @Output() allows the child to send data to a parent component.

What is TemplateRef in angular?

TemplateRef is a class and the way to reference the ng-template in the component or directive class. Using the TemplateRef we can manipulate the template from component code. Remember ng-template is a bunch of HTML tags enclosed in a HTML element <ng-template> 1.

What are directives in angular?

Directives are classes that add additional behavior to elements in your Angular applications. With Angular’s built-in directives, you can manage forms, lists, styles, and what users see. Components—directives with a template. This type of directive is the most common directive type.

What is difference between ng template and Ng container?

To sum up, ng-content is used to display children in a template, ngcontainer is used as a non-rendered container to avoid having to add a span or a div , and ngtemplate allows you to group some content that is not rendered directly but can be used in other places of your template or you code.

What is ViewContainerRef in angular?

ViewContainerRef represents a container where one or more views can be attached. The first thing to mention here is that any DOM element can be used as a view container. What’s interesting is that Angular doesn’t insert views inside the element, but appends them after the element bound to ViewContainer .

What is ComponentRef in angular?


Represents a component created by a ComponentFactory . Provides access to the component instance and related objects, and provides the means of destroying the instance.

What is nativeElement in angular?

Angular ElementRef is a wrapper around a native element inside of a View. It’s simply a class that wraps native DOM elements in the browser and allows you to work with the DOM by providing the nativeElement object which exposes all the methods and properties of the native elements.

What is createEmbeddedView?

createEmbeddedView is used to create a view using TemplateRef. TemplateRef is created by Angular compiler when it encounters ng-template tag in your component HTML. It is created by Angular compiler when you specify a component in the bootstrap property of the module so that compiler generates a factory for it.

How do you use ViewContainerRef?

Get ViewContainerRef with ViewChild:

We can use the ViewChild decorator to grab any element in our view and read him as ViewContainerRef . In this example, the container element is the “div” element, and the template will be inserted as a sibling of this “div.”

What is views in angular?

Angular is a platform and framework for building single-page client applications using HTML and TypeScript. Angular is written in TypeScript. Components define views, which are sets of screen elements that Angular can choose among and modify according to your program logic and data.

How do I get rid of ViewContainerRef?

remove() link

The 0-based index of the view to destroy. If not specified, the last view in the container is removed. Optional. Default is undefined .

How do you destroy components in angular 6?

To force a component to be destroyed, you use the HostListener from the Angular Core library. When using HostListener , you specify the event you want to listen to on the host of the component. In our case, we listen for the unloaded event so that when the page is unloaded, ngOnDestroy() will be triggered.

What is angular ComponentFactoryResolver?


A simple registry that maps Components to generated ComponentFactory classes that can be used to create instances of components. Use to obtain the factory for a given component type, then use the factory’s create() method to create a component of that type.