I have a div with the id of 1. I'm trying to set the display to none dynamically. Is there an Angular way of doing this. Currently, I'm using vanilla javascript. I was asking about doing this dynamically because there will be over 60 divs that will be created from an array.
In my html
<div *ngFor="let item of items; i = index;">
<div id={{i}} (click)=hideDiv()></div>
</div>
In my method
hideDiv() {
return document.getElementById('1').style.display = "none";
}
That works but I'm looking for the Angular way of doing the above.
It was suggested that I use #ViewChild. Here's what I've changed. I can't use a Template Reference Variable as the html divs are created dynamically. Unless someone can let me know how to create the template variables dynamically. Although I don't think it's possible to create template variables with a loop.
#ViewChild('imgId', { static: true }) elementRef: ElementRef<HTMLDivElement>;
imgId: string;
Then in the method I have:
this.imgId = event.path[0].attributes[1].value;
this.elementRef.nativeElement.style.display = "none";
The event.path[0].attributes[1].value gets me the id of the image. The imgId shows when I console log it. It's still not changing the display on the div to none. Also I'm getting the error:
Cannot read properties of undefined (reading 'nativeElement')
Yes, you can use the ViewChild query in Angular to do this. In your component, define a query like this:
#ViewChild('#1') elementRef: ElementRef<HTMLDivElement>;
Implement the AfterViewInit interface in your component, and inside it, use this:
this.elementRef.nativeElement.style.display = "none";
You can simply use ngIf for this
Component
shouldDisplay: boolean = true;
hide(): void {
this.shouldDisplay = false;
}
show(): void {
this.shouldDisplay = true;
}
Html
<button (click)="hide()">Hide</button>
<button (click)="show()">Show</button>
<div *ngIf="shouldDisplay">this is the content</div>
Here is the working example
This is the Angular way:
template
<div *ngIf="showMe"></div>
or
<div [hidden]="!showMe"></div>
TypeScript:
showMe: boolean;
hideDiv() {
this.showMe = false;
}
For dynamic items where your don't know how many you will get the best approach would be to add a directive that would store and adjust that for you:
#Directive({ selector: '[hide-me]' })
export class HideDirective {
#Input() id!: string;
#HostBinding('style.display')
shouldShow: string = '';
}
then in your component just address them by ID:
#Component({
selector: 'my-app',
styleUrls: ['./app.component.css'],
template: `
<div *ngFor="let item of items; let index = index;">
<div hide-me id="{{index}}" (click)="hideDiv(index)">Some value</div>
</div>
`,
})
export class AppComponent {
#ViewChildren(HideDirective) hideDirectives!: QueryList<HideDirective>;
items = [null, null, null];
hideDiv(id: number) {
this.hideDirectives.find((p) => p.id === id.toString()).shouldShow = 'none';
}
}
Stackblitz: https://stackblitz.com/edit/angular-ivy-pnrdhv?file=src/app/app.component.ts
An angular official example: https://stackblitz.com/edit/angular-ivy-pnrdhv?file=src/app/app.component.ts
How about passing the div reference to the hideDiv method directly in the Dom using a template variable like this.
<div *ngFor="let item of items; i = index;">
<div #divElement (click)=hideDiv(divElement)></div>
And in your hide div method you will have access to the element directly
hideDiv(div) { div.style.display = "none";}
Here is a Stackblitz example
https://stackblitz.com/edit/angular-ivy-w1s3jl
There are many ways to do this, but in my opinion this is a simple solution the achieves your goal with less code.
PS:
It is always recommended to use the angular Renderer2 to manipulate Dom elements. This service has the method setStyle which you can use for your code.
I am working a front-end application with Angular 5, and I need to have a search box hidden, but on click of a button, the search box should be displayed and focused.
I have tried a few ways found on StackOverflow with directive or so, but can't succeed.
Here is the sample code:
#Component({
selector: 'my-app',
template: `
<div>
<h2>Hello</h2>
</div>
<button (click) ="showSearch()">Show Search</button>
<p></p>
<form>
<div >
<input *ngIf="show" #search type="text" />
</div>
</form>
`,
})
export class App implements AfterViewInit {
#ViewChild('search') searchElement: ElementRef;
show: false;
name:string;
constructor() {
}
showSearch(){
this.show = !this.show;
this.searchElement.nativeElement.focus();
alert("focus");
}
ngAfterViewInit() {
this.firstNameElement.nativeElement.focus();
}
The search box is not set to focus.
How can I do that?
Edit 2022:
Read a more modern way with #Cichy's answer below
Modify the show search method like this
showSearch(){
this.show = !this.show;
setTimeout(()=>{ // this will make the execution after the above boolean has changed
this.searchElement.nativeElement.focus();
},0);
}
You should use HTML autofocus for this:
<input *ngIf="show" #search type="text" autofocus />
Note: if your component is persisted and reused, it will only autofocus the first time the fragment is attached. This can be overcome by having a global DOM listener that checks for autofocus attribute inside a DOM fragment when it is attached and then reapplying it or focus via JavaScript.
Here is an example global listener, it only needs to be placed in your spa application once and autofocus will function regardless of how many times the same fragment is reused:
(new MutationObserver(function (mutations, observer) {
for (let i = 0; i < mutations.length; i++) {
const m = mutations[i];
if (m.type == 'childList') {
for (let k = 0; k < m.addedNodes.length; k++) {
const autofocuses = m.addedNodes[k].querySelectorAll("[autofocus]"); //Note: this ignores the fragment's root element
console.log(autofocuses);
if (autofocuses.length) {
const a = autofocuses[autofocuses.length - 1]; // focus last autofocus element
a.focus();
a.select();
}
}
}
}
})).observe(document.body, { attributes: false, childList: true, subtree: true });
This directive will instantly focus and select any text in the element as soon as it's displayed. This might require a setTimeout for some cases, it has not been tested much.
import { Directive, ElementRef, OnInit } from '#angular/core';
#Directive({
selector: '[appPrefixFocusAndSelect]',
})
export class FocusOnShowDirective implements OnInit {
constructor(private el: ElementRef) {
if (!el.nativeElement['focus']) {
throw new Error('Element does not accept focus.');
}
}
ngOnInit(): void {
const input: HTMLInputElement = this.el.nativeElement as HTMLInputElement;
input.focus();
input.select();
}
}
And in the HTML:
<mat-form-field>
<input matInput type="text" appPrefixFocusAndSelect [value]="'etc'">
</mat-form-field>
html of component:
<input [cdkTrapFocusAutoCapture]="show" [cdkTrapFocus]="show">
controler of component:
showSearch() {
this.show = !this.show;
}
..and do not forget about import A11yModule from #angular/cdk/a11y
import { A11yModule } from '#angular/cdk/a11y'
I'm going to weigh in on this (Angular 7 Solution)
input [appFocus]="focus"....
import {AfterViewInit, Directive, ElementRef, Input,} from '#angular/core';
#Directive({
selector: 'input[appFocus]',
})
export class FocusDirective implements AfterViewInit {
#Input('appFocus')
private focused: boolean = false;
constructor(public element: ElementRef<HTMLElement>) {
}
ngAfterViewInit(): void {
// ExpressionChangedAfterItHasBeenCheckedError: Expression has changed after it was checked.
if (this.focused) {
setTimeout(() => this.element.nativeElement.focus(), 0);
}
}
}
This is working i Angular 8 without setTimeout:
import {AfterContentChecked, Directive, ElementRef} from '#angular/core';
#Directive({
selector: 'input[inputAutoFocus]'
})
export class InputFocusDirective implements AfterContentChecked {
constructor(private element: ElementRef<HTMLInputElement>) {}
ngAfterContentChecked(): void {
this.element.nativeElement.focus();
}
}
Explanation:
Ok so this works because of: Change detection. It's the same reason that setTimout works, but when running a setTimeout in Angular it will bypass Zone.js and run all checks again, and it works because when the setTimeout is complete all changes are completed. With the correct lifecycle hook (AfterContentChecked) the same result can be be reached, but with the advantage that the extra cycle won't be run. The function will fire when all changes are checked and passed, and runs after the hooks AfterContentInit and DoCheck. If i'm wrong here please correct me.
More one lifecycles and change detection on https://angular.io/guide/lifecycle-hooks
UPDATE:
I found an even better way to do this if one is using Angular Material CDK, the a11y-package.
First import A11yModule in the the module declaring the component you have the input-field in.
Then use cdkTrapFocus and cdkTrapFocusAutoCapture directives and use like this in html and set tabIndex on the input:
<div class="dropdown" cdkTrapFocus cdkTrapFocusAutoCapture>
<input type="text tabIndex="0">
</div>
We had some issues with our dropdowns regarding positioning and responsiveness and started using the OverlayModule from the cdk instead, and this method using A11yModule works flawlessly.
In Angular, within HTML itself, you can set focus to input on click of a button.
<button (click)="myInput.focus()">Click Me</button>
<input #myInput></input>
To make the execution after the boolean has changed and avoid the usage of timeout you can do:
import { ChangeDetectorRef } from '#angular/core';
constructor(private cd: ChangeDetectorRef) {}
showSearch(){
this.show = !this.show;
this.cd.detectChanges();
this.searchElement.nativeElement.focus();
}
I'm having same scenario, this worked for me but i'm not having the "hide/show" feature you have. So perhaps you could first check if you get the focus when you have the field always visible, and then try to solve why does not work when you change visibility (probably that's why you need to apply a sleep or a promise)
To set focus, this is the only change you need to do:
your Html mat input should be:
<input #yourControlName matInput>
in your TS class, reference like this in the variables section (
export class blabla...
#ViewChild("yourControlName") yourControl : ElementRef;
Your button it's fine, calling:
showSearch(){
///blabla... then finally:
this.yourControl.nativeElement.focus();
}
and that's it.
You can check this solution on this post that I found, so thanks to -->
https://codeburst.io/focusing-on-form-elements-the-angular-way-e9a78725c04f
There is also a DOM attribute called cdkFocusInitial which works for me on inputs.
You can read more about it here: https://material.angular.io/cdk/a11y/overview
Only using Angular Template
<input type="text" #searchText>
<span (click)="searchText.focus()">clear</span>
When using an overlay/dialog, you need to use cdkFocusInitial within cdkTrapFocus and cdkTrapFocusAutoCapture.
CDK Regions:
If you're using cdkFocusInitial together with the CdkTrapFocus directive, nothing will happen unless you've enabled the cdkTrapFocusAutoCapture option as well. This is due to CdkTrapFocus not capturing focus on initialization by default.
In the overlay/dialog component:
<div cdkTrapFocus cdkTrapFocusAutoCapture>
<input cdkFocusInitial>
</div>
#john-white The reason the magic works with a zero setTimeout is because
this.searchElement.nativeElement.focus();
is sent to the end of the browser callStack and therefore executed last/later, its not a very nice way of getting it to work and it probably means there is other logic in the code that could be improved on.
Easier way is also to do this.
let elementReference = document.querySelector('<your css, #id selector>');
if (elementReference instanceof HTMLElement) {
elementReference.focus();
}
I am working on Angular 6 on a pretty simple example.
I am creating a Directive that I can put on my textareas so that they resize themselves automatically.
However, I have an issue using host binding. I want to check if resize is needed before resizing, but I cannot check: this.height gives undefined by default.
Even worse, if it has been resized manually, this.height remains undefined anyway.
I've tried using the #Input decorator on top of the #HostBinding, but this just sets an initial value, and then when resizing, height doesn't match the real size of the element anymore.
I can't seem to find out why it doesn't work, could you please help ?
Also I am conscious that an alternative to what I'm trying to do would be to just set the height of my directive to the native element scrollheight without checking prior, but then I wouldn't understand why my height value is undefined/doesn't dynamically update.
Here is my code:
simple.component.html
<textarea type="text"
class="form-control mb-1"
appAutoResizeTextArea></textarea>
simple.component.ts
import { Component, OnInit } from '#angular/core';
#Component({
selector: 'app-simple-component',
templateUrl: './simple.component.html',
styleUrls: ['./simple.component.css']
})
export class SimpleComponent implements OnInit {
constructor() { }
ngOnInit() {
}
}
auto-resize-text-area.directive.ts
import { Directive, ElementRef, HostListener, Renderer2, HostBinding, Input } from '#angular/core';
#Directive({
selector: '[appAutoResizeTextArea]',
})
export class AutoResizeTextAreaDirective {
#HostBinding('style.height.px') height;
#HostListener('input')
onKeyDown(){
console.log(this.height); // gives 'undefined'
if(this.height < this.el.nativeElement.scrollHeight || this.height > this.el.nativeElement.scrollHeight)
this.height = this.el.nativeElement.scrollHeight;
}
constructor(private el:ElementRef, private renderer:Renderer2) { }
}
Thanks for your help
At the moment, I'm using ELEMENTREF to access the DOM through the Redenrer2. Here's a basic example:
import { Directive, Renderer2, ElementRef } from '#angular/core';
#Directive({
selector: '[appHighlight]'
})
export class HighlightDirective {
constructor(private renderer: Renderer2, private el: ElementRef) {
this.renderer.setStyle(this.el.nativeElement, 'background', 'yellow');
}
}
The above code was just a test to leave the syntax highlight with the yellow color.
However, I need to know how do I access the previous element and capture the width of it to move to a left-style property?
Ex: Former brother has the width of 400px. The current element has the left of 400px.
I'm counting on the collaboration.
You can get the parent element:
let parent = this.renderer.parentNode(this.elementRef.nativeElement);
and then select his child somehow, maybe give them incrementing ID's:
let sibling = parent.querySelector('#child5');
and then you have siblings width:
let width = sibling.offsetWidth;.
Hope that helps.
I have a component that I needs to be hidden when a property is true. Is there a way to solve this within the component itself.
Example:
#Component({
selector: 'prio-tab',
changeDetection: ChangeDetectionStrategy.OnPush,
template:
`
<div [hidden]="!active">
stuff
</div>
`
})
export class PrioTabComponent {
#Input() title;
active:boolean = false;
}
Here I would like to have the actual "prio-tab" element to depend on active-flag. Not just the content inside prio-tab.
Or is it maybe possible to use itself when declaring the prio-tab tag, like this:
<prio-tab [hidden]="this.active">
stuff
</prio-tab>
I guess a working solution would be to create a reference to the prio-tab component in its parent and then go through the parent. But how would I do if I have multiple prio-tab's ?
You can use #HostBinding()
export class PrioTabComponent {
#Input() title;
#HostBinding('hidden')
active:boolean = false;
}