Quick Answer: What Is Static In ViewChild?

What is decorator in angular?

Decorators are proposed for a future version of JavaScript, but the Angular team really wanted to use them, and they have been included in TypeScript.

Decorators are functions that are invoked with a prefixed @ symbol, and immediately followed by a class , parameter, method or property..

What is the difference between ViewChild and ContentChild?

It is used to access Child Component in the Parent Component. Any directive, component, and element which is part of component template is accessed as ViewChild. Whereas, any element or component which is projected inside is accessed as ContentChild.

What is a directive in angular?

At the core, a directive is a function that executes whenever the Angular compiler finds it in the DOM. Angular directives are used to extend the power of the HTML by giving it new syntax. Each directive has a name — either one from the Angular predefined like ng-repeat , or a custom one which can be called anything.

What is 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 TemplateRef in angular?

TemplateRef holds the createEmbeddedView function. It instantiates the template as an embedded view. A second @ViewChild query provides a reference to ng-container as a ViewContainerRef . Embedded views only attach to other views, never the DOM. The ViewContainerRef references the view that takes in the embedded view.

What is static true in ViewChild?

The static option for @ViewChild() and @ContentChild() queries determines when the query results become available. With static queries (static: true), the query resolves once the view has been created, but before change detection runs.

What is static false in ViewChild?

With dynamic queries (static: false), the query resolves after either ngAfterViewInit() or ngAfterContentInit() for @ViewChild() and @ContentChild() respectively. The result will be updated for changes to our view, such as changes to ngIf and ngFor blocks.

What is the use of ViewChild?

Conclusion. 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 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.

Why is ngOnChanges called before ngOnInit?

ngOnChanges() You might want to wonder why ngOnInit hook is not called first, but that is because Angular counts that very first class initialization as a data property change. So the hook that gets called once a data property change (like resetting values) occurs is ngOnChanges().

What is ViewChild?

A ViewChild is a component, directive, or element as a part of a template. If we want to access a child component, directive, DOM element inside the parent component, we use the decorator @ViewChild() in Angular. … Since the child component can be located inside the parent component, it can accessed as @ViewChild.

What is the use of ngAfterViewInit?

ngAfterViewInit() is a lifecycle hook that is called after Angular has fully initialized a component’s views. ngAfterViewInit() is used to handle any additional initialization tasks. Find the AfterViewInit interface code from Angular doc.

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 AfterViewInit in angular?

AfterViewInitlink A lifecycle hook that is called after Angular has fully initialized a component’s view. Define an ngAfterViewInit() method to handle any additional initialization tasks.

Is ngOnChanges called before ngOnInit?

ngOnChanges: Called every time a data-bound input property changes. It’s called a first time before the ngOnInit hook. The hook receives a SimpleChanges object that contains the previous and current values for the data-bound inputs properties.

What is OnInit in angular?

ngOnInit is a life cycle hook called by Angular to indicate that the Angular is done creating the component. In order to use OnInit we have to import it in the component class like this: import {Component, OnInit} from ‘@angular/core’; Actually implementing OnInit in every component is not mandatory.

What is Contentchild in angular?

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 the difference between ViewChild and ViewChildren?

Another critical difference is that @ViewChild returns a single native DOM element as a reference, while the @ViewChildren decorator returns the list of different native DOM elements in the form of QueryList , which contains the set of elements.