How can I select an element in a component template

Question

Does anybody know how to get hold of an element defined in a component template  Polymer makes it really easy with the   and      I was just wondering how to go about it in Angular   Take the example from the tutorial   import  Component  from   angular core     Component       selector  display       template         lt input  myname  input   updateName myname value    gt        lt p gt My name     myName   lt  p gt               export class DisplayComponent       myName  string    Aman       updateName input  String            this myName   input            How do I catch hold or get a reference of the p or input element from within the class definition

User · Accepted Answer

Instead of injecting ElementRef and using querySelector or similar from there  a declarative way can be used instead to access elements in the view directly      lt input  myname gt       ViewChild  myname   input     element  ngAfterViewInit       console log this input nativeElement value       StackBlitz example    ViewChild   supports directive or component type as parameter  or the name  string  of a template variable     ViewChildren   also supports a list of names as comma separated list  currently no spaces allowed  ViewChildren  var1 var2 var3        ContentChild   and  ContentChildren   do the same but in the light DOM   lt ng-content gt  projected elements     descendants   ContentChildren   is the only one that allows to also query for descendants    ContentChildren SomeTypeOrVarName   descendants  true   someField       descendants  true  should be the default but is not in 2 0 0 final and it s considered a bug  This was fixed in 2 0 1  read  If there are a component and directives the read parameter allows to specify which instance should be returned   For example ViewContainerRef that is required by dynamically created components instead of the default ElementRef   ViewChild  myname     read  ViewContainerRef    target    subscribe changes  Even though view children are only set when ngAfterViewInit   is called and content children are only set when ngAfterContentInit   is called  if you want to subscribe to changes of the query result  it should be done in ngOnInit    https   github com angular angular issues 9689 issuecomment-229247134   ViewChildren SomeType  viewChildren   ContentChildren SomeType  contentChildren   ngOnInit       this viewChildren changes subscribe changes   gt  console log changes      this contentChildren changes subscribe changes   gt  console log changes        direct DOM access  can only query DOM elements  but not components or directive instances   export class MyComponent     constructor private elRef ElementRef       ngAfterViewInit         var div   this elRef nativeElement querySelector  div        console log div             for transcluded content   ngAfterContentInit         var div   this elRef nativeElement querySelector  div        console log div           get arbitrary projected content  See Access transcluded content

User · Answer

In case you are using Angular Material  you can take advantage of cdkFocusInitial directive  Example   lt input matInput cdkFocusInitial gt  Read more here  https   material angular io cdk a11y overview regions

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import the ViewChild decorator from  angular core  like so   HTML Code    lt form  f  ngForm  gt                  lt  form gt    TS Code   import   ViewChild   from   angular core    class TemplateFormComponent       ViewChild  f   myForm  any                        now you can use  myForm  object to access any element within it in the class   Source

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Angular 4   Use renderer selectRootElement with a CSS selector to access the element  I ve got a form that initially displays an email input  After the email is entered  the form will be expanded to allow them to continue adding information relating to their project  However  if they are not an existing client  the form will include an address section above the project information section  As of now  the data entry portion has not been broken up into components  so the sections are managed with  ngIf directives  I need to set focus on the project notes field if they are an existing client  or the first name field if they are new  I tried the solutions with no success  However  Update 3 in this answer gave me half of the eventual solution  The other half came from MatteoNY s response in this thread  The result is this  import   NgZone  Renderer   from   angular core    constructor private ngZone  NgZone  private renderer  Renderer      setFocus selector  string   void       this ngZone runOutsideAngular      gt            setTimeout      gt                this renderer selectRootElement selector  focus               0              submitEmail email  string   void          Verify existence of customer             if  this newCustomer            this setFocus   firstname          else           this setFocus   description             Since the only thing I m doing is setting the focus on an element  I don t need to concern myself with change detection  so I can actually run the call to renderer selectRootElement outside of Angular  Because I need to give the new sections time to render  the element section is wrapped in a timeout to allow the rendering threads time to catch up before the element selection is attempted  Once all that is setup  I can simply call the element using basic CSS selectors  I know this example dealt primarily with the focus event  but it s hard for me that this couldn t be used in other contexts  UPDATE  Angular dropped support for Renderer in Angular 4 and removed it completely in Angular 9  This solution should not be impacted by the migration to Renderer2  Please refer to this link for additional information  Renderer migration to Renderer2

User · Answer

For components inside  ngIf  another approach  The component I wanted to select was inside a div s  ngIf statement  and  jsgoupil s answer above probably works  Thanks  jsgoupil    but I ended up finding a way to avoid using  ngIf  by using CSS to hide the element  When the condition in the  className  is true  the div gets displayed  and naming the component using   works and it can be selected from within the typescript code  When the condition is false  it s not displayed  and I don t need to select it anyway  Component   Component       selector   bla       templateUrl   bla component html       styleUrls    bla component scss      export class BlaComponent implements OnInit  OnDestroy        ViewChild  myComponentWidget    static  true   public myComponentWidget  any       Input  action   action  ActionType     an enum defined in our code   action could also be declared locally   constructor        etc        this lets you use an enum in the HMTL  ActionType SomeType  public get actionTypeEnum    typeOf ActionType       return ActionType     public someMethodXYZ  void       this myComponentWidget someMethod       use it like that  assuming the method exists    and then in the bla component html file   lt div  className   quot action     actionTypeEnum SomeType    show-it     do-not-show  quot  gt        lt my-component  myComponentWidget etc gt  lt  my-component gt   lt  div gt   lt div gt       lt button type  quot reset quot  class  quot bunch-of-classes quot   click   quot someMethodXYZ   quot  gt           lt span gt XYZ lt  span gt       lt  button gt   lt  div gt      and the CSS file     ng-deep        show-it            display  block       example  actually a lot more css in our code            do-not-show           display  none

User · Answer

Selecting target element from the list  It is easy to select particular element from the list of same elements   component code   export class AppComponent     title    app      listEvents           name   item1    class          name   item2    class              name   item3    class          name   item4    class               selectElement item  string  value  number        console log  item   item   value   value       if this listEvents value  class                this listEvents value  class  selected         else         this listEvents value  class                    html code    lt ul  ngFor  let event of listEvents  let i   index  gt      lt li   click   selectElement event name  i    class   event class  gt       event name     lt  li gt      css code    selected     color  red    background blue

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import  Component ViewChild  from   angular core    Import View Child     Component       selector  display      template          lt input  myname  input     updateName myname value    gt        lt p gt  My name     myName   lt  p gt            export class DisplayComponent     ViewChild  myname  inputTxt ElementRef    create a view child       myName  string       updateName  Function      constructor             this myName    Aman           this updateName   function input  String                this inputTxt nativeElement value this myName                  assign to it the value

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Note  This doesn t apply to Angular 6 and above as ElementRef became ElementRef lt T gt  with T denoting the type of nativeElement   I would like to add that if you are using ElementRef  as recommended by all answers  then you will immediately encounter the problem that ElementRef has an awful type declaration that looks like  export declare class ElementRef     nativeElement  any      this is stupid in a browser environment where nativeElement is an HTMLElement   To workaround this you can use the following technique  import  Inject  ElementRef as ErrorProneElementRef  from   angular core    interface ElementRef     nativeElement  HTMLElement      Component        export class MyComponent     constructor  Inject ErrorProneElementRef  readonly elementRef  ElementRef

User · Answer

For people trying to grab the component instance inside a  ngIf or  ngSwitchCase  you can follow this trick   Create an init directive   import       Directive      EventEmitter      Output      OnInit      ElementRef   from   angular core     Directive       selector    init      export class InitDirective implements OnInit       constructor private ref  ElementRef           Output   init  EventEmitter lt ElementRef gt    new EventEmitter lt ElementRef gt          ngOnInit             this init emit this ref             Export your component with a name such as myComponent   Component       selector   wm-my-component       templateUrl   my-component component html       styleUrls    my-component component css        exportAs   myComponent     export class MyComponent           Use this template to get the ElementRef AND MyComponent instance   lt div  ngSwitch   type  gt       lt wm-my-component             myComponent  myComponent              ngSwitchCase  Type MyType              init   init  event  myComponent   gt       lt  wm-my-component gt   lt  div gt    Use this code in TypeScript  init myComponentRef  ElementRef  myComponent  MyComponent

User · Answer

to get the immediate next sibling  use this  event source  elementRef nativeElement nextElementSibling

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import   Component  ElementRef  OnInit   from   angular core     Component     selector  display     template       lt input  input   updateName  event target value   gt      lt p gt  My name      myName    lt  p gt         class DisplayComponent implements OnInit     constructor public element  ElementRef        this element nativeElement     lt - your direct element reference        ngOnInit         var el   this element nativeElement      console log el         updateName value                       Example updated to work with the latest version  For more details on native element  here

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Mimimum example for quick usage   import   Component  ElementRef  ViewChild  from   angular core     Component     selector   my-app     template         lt input  inputEl value  hithere  gt         styleUrls       app component css       export class AppComponent       ViewChild  inputEl   inputEl ElementRef      ngAfterViewInit         console log this inputEl            Put a template reference variable on the DOM element of interest  In our example this is the  inputEl on the  lt input gt  tag  In our component class inject the DOM element via the  ViewChild decorator Access the element in the ngAfterViewInit lifecycle hook    Note   If you want to manipulate the DOM elements use the Renderer2 API instead of accessing the elements directly  Permitting direct access to the DOM can make your application more vulnerable to XSS attacks

User · Answer

You can get a handle to the DOM element via ElementRef by injecting it into your component s constructor  constructor private myElement  ElementRef           Docs  https   angular io docs ts latest api core index ElementRef-class html

[angular] How can I select an element in a component template?

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