What is ElementRef in angular

According to the official docs. 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 an ElementRef?

Angular ElementRef is a wrapper around a native DOM element (HTML element) object. It contains the property nativeElement , which holds the reference to the underlying DOM object. We can use it to manipulate the DOM. We use the ViewChild to get the ElementRef of an HTML element in the component class.

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.

Is ElementRef safe?

Security Risk As per Angular docs, ElementRef has direct access to DOM, and it makes your application more vulnerable to XSS attacks. Use this, when you have no option left to access the DOM element.

What is Renderer and ElementRef in Angular 2?

The Renderer is a class that is a partial abstraction over the DOM. Using the Renderer for manipulating the DOM doesn’t break server-side rendering or Web Workers (where direct access to the DOM would break). ElementRef is a class that can hold a reference to a DOM element.

What is renderer in Angular?

The Renderer class is a built-in service that provides an abstraction for UI rendering manipulations. For example, you need to set the focus on an input element, so you may be tempted to do something like: … Remember that Angular is a platform, and the browser is just one option for where we can render our app.

What is ViewChild and ViewChildren in Angular?

Both ViewChild and ViewChildren are used to communicate between the components to access the data. @ViewChild and @ViewChildren are the types of decorators used to access the child component class and its different properties into the parent component. It’s similar to the inheritance.

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.

When should I use Renderer2?

The Renderer2 allows us to manipulate the DOM elements, without accessing the DOM directly. It provides a layer of abstraction between the DOM element and the component code. Using Renderer2 we can create an element, add a text node to it, append child element using the appendchild method., etc.

How do you use a directive?

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.

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What is ViewChild used for?

5 Answers. The ViewChild decorator is used to gain access to a child component, found in the template, so that you can access its properties and methods.

What is static 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 read in ViewChild?

With {read: SomeType} you tell what type should be returned from the element with the #myname template variable. If you don’t provide the read parameter, @ViewChild() returns the. ElementRef instance if there is no component applied, or the. component instance if there is.

What is the meaning of renderer?

renderer (plural renderers) One who, or that which, renders. A vessel in which lard, tallow, etc., is rendered. (computer graphics) A software or hardware process that generates a visual image from a model.

Why would you use renderer methods instead of using native element methods in angular?

Using renderer service will provide us opportunity to be able to execute manipulations in non-DOM environments like native mobile, desktop and web worker rendering.

What is ContentChild and ContentChildren?

The ContentChild & ContentChildren are decorators, which we use to Query and get the reference to the Projected Content in the DOM. Projected content is the content that this component receives from a parent component. The ContentChild & ContentChildren is very similar to the ViewChild & ViewChildren.

What is the decorator in Angular?

Decorators are a design pattern that is used to separate modification or decoration of a class without modifying the original source code. In AngularJS, decorators are functions that allow a service, directive or filter to be modified prior to its usage.

What is query list in Angular?

The QueryList is unmodifiable list of items that Angular keeps up-to-date when the state of the application changes. The ViewChildren and ContentChildren uses QueryList to store elements or directives from view DOM and content DOM respectively.

What is virtual Dom in angular?

Virtual DOM is a collection of modules designed to provide a declarative way of representing the DOM for your app. So instead of updating the DOM when your application state changes, you simply create a virtual tree or Virtual Tree, which looks like the DOM state that you want.

What is DOM in angular8?

Angular 8 Directives: Directives are instructions in the DOM (Document Object Model). It specifies how to place our business logic in Angular. The directive is markers on a DOM element that tell Angular to attach a specified behavior to that DOM element or even transform the DOM element and its children.

What is DOM manipulation in Angular?

Angular offers multiple ways to handle DOM Manipulation . EVENT BINDING : The flow of information from elements in a component to the corresponding component’s class is event binding (HTML Template to TS) . Event binding works without having to define a template reference variable.

How do you manipulate DOM in Angular 8?

1. Step 2: setAttribute of native DOM element is using to add the attribute. …
2. Step 1: Inject ElementRef into a directive file’s constructor. …
3. Step 2: Add @input decorator to the directive. …
4. Step 3: Use setAttribute() native element method to add an attribute in ngOnInit() lifecycle hook.

What is view container 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 .

How do I use TemplateRef?

Access a TemplateRef instance by placing a directive on an <ng-template> element (or directive prefixed with * ). The TemplateRef for the embedded view is injected into the constructor of the directive, using the TemplateRef token.

What does ng-content do?

ng-content is used to project content into Angular components. In plain HTML, you can create children in any element, like this: … except if you tell Angular where to display it in the parent template using ng-content.

Why directives are used in Angular?

Directives are classes that add additional behavior to elements in your Angular applications. Use Angular’s built-in directives to manage forms, lists, styles, and what users see. … Structural directives—directives that change the DOM layout by adding and removing DOM elements.

What is injector in AngularJS?

An injector is a service locator. It is used to retrieve object instances as defined by provider, instantiate types, invoke methods and load modules.

What is ngIf in Angular?

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.

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 8?

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 content child 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.