What are @viewchild and @viewchildren decorators in Angular 8?
The @ViewChild and @ViewChildren decorators in Angular provide a way to access and manipulate DOM elements, directives and components. In this tutorial, we'll see an Angular 8 example of how to use the two decorators.
What is the use of viewchild in React component?
The ViewChild or ViewChildren decorators are used to Query and get the reference of the DOM element in the Component. ViewChild returns the first matching element and ViewChildren returns all the matching elements as a QueryList of items. We can use these references to manipulate element properties in the component.
What is the use of viewchild?
Now, let us learn ViewChild using few examples. One of the use cases of ViewChild is to get the reference of the Child Component in the Parent Component and manipulate its properties. This is one of the ways by which the Parent can communicate with the child components.
What is the difference between viewchildren and querylist in Angular 2?
It is very much similar to syntax of viewChild except for the static option. The ViewChildren is always resolved after the change detection is run. i.e why it does not have static option. And also you cannot refer to it in the ngOnInit hook as it is yet to initialize. The QueryList is the return type of ViewChildren and contentChildren .
What is ViewChild and ViewChildren in Angular?
The @ViewChild and @ViewChildren decorators in Angular provide access to child elements in the view DOM by setting up view queries. A view query is a requested reference to a child element within a component view which contains metadata of the element.
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 the use of @ViewChild in Angular 7?
ViewChildlink Property decorator that configures a view query. The change detector looks for the first element or the directive matching the selector in the view DOM. If the view DOM changes, and a new child matches the selector, the property is updated.
What is ContentChild and ContentChildren?
ContentChild & ContentChildren The concept of a content child is similar to that of a view child but the content children of the given component are the child elements that are projected into the component from the host component. In our example application we are projecting one joke in from the host AppComponent .
What is @ViewChildren?
Returns the specified elements or directives from the view DOM as QueryList. For example, let's create a simple alert component. Now let's use this component multiple times in our app component and use the @ViewChildren decorator.
What is the use of ViewChildren?
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 difference between @ViewChild and ViewChildren?
The ViewChild or ViewChildren decorators are used to Query and get the reference of the DOM element in the Component. ViewChild returns the first matching element and ViewChildren returns all the matching elements as a QueryList of items. We can use these references to manipulate element properties in the component.
What is the use of ElementRef?
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 the difference between @ViewChild and @input?
While Angular inputs/outputs should be used when sharing data to and from child components, ViewChild should be used when trying to utilize properties and methods of the child component directly in the parent component.
What is the purpose of ContentChildren?
ContentChildren is a parameter decorator that is used to fetch the QueryList of elements or directives from the content DOM. The QueryList is updated whenever the child element/component is added or removed. The child element reference is set in QueryList just before the ngAfterContentInit lifecycle Hook method.
What is QueryList in Angular?
An unmodifiable list of items that Angular keeps up to date when the state of the application changes.
What is Templateref in Angular?
TemplateReflink Represents an embedded template that can be used to instantiate embedded views. To instantiate embedded views based on a template, use the ViewContainerRef method createEmbeddedView() .
What is the difference between ViewChild and ViewChildren?
Working with @ViewChildren is similar to @ViewChild, but the difference between the two is @ViewChildren provides a list of element references rather than returning a single reference. It is used to reference multiple elements. We can then iterate the list of the element referenced by the variable.
What is the difference between ElementRef and TemplateRef?
ElementRef refers to an element of the DOM, whereas TemplateRef represents an embedded template (usually a component template). So to summarize, the template ref can contain several element refs, but the element ref can not contain a template ref.
What is the difference between @ViewChild and @input?
While Angular inputs/outputs should be used when sharing data to and from child components, ViewChild should be used when trying to utilize properties and methods of the child component directly in the parent component.
What is content DOM and view DOM?
The content DOM defines the innerHTML of directive elements . Conversely, the view DOM is a component's template (component.html) excluding any template HTML nested within a directive. Follow this answer to receive notifications. answered Sep 21, 2020 at 14:01.