Develop Reference

Losing the focus on an input that appears conditionally - Angular 7 [duplicate]

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();
}

Clone/Copy a Method in Javascript?

How does one clone or copy a method such that no reference to the original method is maintained?
I am trying to copy a click function on an element using the DOM and assign it to another element so I can remove the first element from the DOM without losing the function reference on the other element. I am doing this in a directive.
element.click = parent.click //need a better way to copy
element.click() //works
remove(parent)
element.click() //doesn't work
The reason why I am doing this is because I am removing the parent-wrapper tag, which has a (click) method assigned to it, so that just its inner button template remains. However, because I am removing the wrapper tag, the (click) on the parent tag is not being passed to the template button tag.
For instance, I have an app-button component with a button in its template.
Currently this is rendered:
<app-button (click) = function(1, 2)>
<button>
</button>
</app-button>
I want the parent tag removed, which I am doing via a DOM manipulation, but want to maintain the (click) function, like:
<button (click) = function(1, 2)>
</button>

I'm not quite sure I understand why you are trying to do what you are doing(or what it is exactly), but from my understanding, you could store a reference to the host element '' in the component class, then you can assign a listener to the <button> element in your template that triggers a click event on that reference:
import { BrowserModule } from '#angular/platform-browser';
import { NgModule, Component, ViewChild, ElementRef, Renderer2, OnInit} from '#angular/core';
#Component({
selector: 'app-root',
template: `
<app-button (click)="foo()"></app-button>
`
})
export class AppComponent {
foo() {
console.log('bar');
}// end function
}// end class
#Component({
selector: 'app-button',
template: `<button #button (click)="onClick()">Click me</button>`
})
export class AppButtonComponent implements OnInit {
#ViewChild('button')
private button:ElementRef;
constructor(
private element:ElementRef,
private renderer:Renderer2
) {}
ngOnInit() {
let parent = this.element.nativeElement.parentElement,
element = this.element.nativeElement,
button = this.button.nativeElement;
this.renderer.insertBefore(parent, button, element );
this.renderer.removeChild(parent, element);
}// end function
onClick() {
let element = this.element.nativeElement;
element.click();
}// end function
}// end class

Remove all occurances of class in angular 2 +

I have just started coding in angular5 and I came across need of removing all class occurances on click event.
Something like below we have in Jquery
$('.m-active').removeClass('m-active');
I am looking for alternative of this in angular2 + (Typescript)

You could use document.querySelector all to remove the class - in the following - I have two divs - iniitally set to be red / green text, but using querySelectorAll - I am removing the red class from the divs.
function toggleRedClass() {
var redDivs = document.querySelectorAll('.red');
if (redDivs.length) {
for(i=0;i<redDivs.length;i++) {
redDivs[i].classList.remove('red');
redDivs[i].classList.add('black')
}
} else {
var blackDivs = document.querySelectorAll('.black');
for(i=0;i<blackDivs.length;i++) {
blackDivs[i].classList.remove('black')
blackDivs[i].classList.add('red')
}
}
}
.red {color:red}
.green {color:green}
<div class="red">test</div>
<div class="green">test1</div>
<button type="button" onclick="toggleRedClass()">Click to toggle the red class</button>

In Angular 2+ better use bindings instead of jQuery
<div [class.my-class]="isMyClass">div 1</div>
<div [class.my-class]="isMyClass">div 2</div>
<button (click)="isMyClass = !isMyClass">toggle</button>
export class MyComponent {
isMyClass:boolean = true;
}

You can create a directive like this :
https://plnkr.co/edit/eKokX0IrsIWIuY9ACUZ4?p=preview
#Directive({
selector: '[class]'
})
export class ClassDirective {
#Input('class') claz;
private _claz;
public set claz(claz){
this._claz = claz;
}
public get claz(){
return this._claz;
}
#HostBinding('class') get hostClass(){
return this.claz;
}
constructor(){
console.log('***');
}
ngOnInit(){
console.log('this.classz',this.claz);
setTimeout(()=>{
this.claz= this.claz.replace('milad','');
},2000)
}
}
I know it doesn't do exactly what you want, but the idea is to create a Directive which has a selector called class and then you have access to all the classes in your application (obviously this component should be declared in your modules).
Then you can do whatever you'd like inside that directive, you can use host binding to override the classes and whatnot.
You can create an event listener to some button, pass the event listener's call back to this directive and let it do whatever you want.

Angular 4 Change form input value to # while tying

I am trying to mimic what is done with passwords, where whatever an user types, it is substituted by •••••••, except that I want to do this for numbers and only show the last four numbers. So far I have the events in my #Directive that capture the keystrokes, but don't actually emit or propagate any change up the stream (in the input) to change the value.
Ex. #####1234
<input id="indTaxId" type="text" name="indTaxId"
[(ngModel)]="payLoadService.individual.taxId"
required maxlength="9" pattern="^[0-9]{9}$"
[lastFourDirective]="payLoadService.individual.taxId"
(lastFourDirectiveOutput)="payLoadService.individual.taxId"
/>
last-four.directive.ts
#Directive({
selector: '[lastFourDirective]'
})
export class LastFourDirective implements OnInit {
private el: HTMLInputElement;
constructor(
private elementRef: ElementRef
) {
this.el = this.elementRef.nativeElement;
}
ngOnInit() {
}
#Input() lastFourDirective: string;
#HostListener('blur', ['$event.target.value'])
onBlur(value) {
console.log("blur", value);
return this.lastFourDigits(value)
}
#HostListener('keyup', ['$event.target.value'])
onKeyup(value) {
console.log("keyup", value);
return this.lastFourDigits(value)
}
private lastFourDigits(taxId: string) {
return taxId.replace(/\d(?=\d{4})/g, '#')
}
}
How can I accomplish this?
PS: I'm not using formControl, above is a sample of my input.

You are using a directive so certainly there is a global need for you to do this in your application. I haven't worked on angular4 (I really thought, somehow I could use a filter here but was unable) but if there isn't a global need for this kind of input box, why don't you write a function in your component itself and trigger it on (keyup) and (blur) events. For example:
<input id="indTaxId" type="text" name="indTaxId"
[(ngModel)]= payLoadService.individual.taxId
required maxlength="9" pattern="^[0-9]{9}$"
(keyup)="foo()"
(blur)="foo()"
/>
and in your component:
foo() {
this.payLoadService.individual.taxId = this.payLoadService.individual.taxId.replace(/\d(?=\d{4})/g, '#');
}
Now I don't have an answer if you want to implement through a directive, but I can suggest you another solution if you want this functionality at multiple places, you can make a password input component containing only this functionality i.e. only the input box and use this component wherever you want such input boxes.

How do I detect change to ngModel on a select tag (Angular 2)?

I am attempting to detect a change on ngModel in a <select> tag. In Angular 1.x, we might solve this with a $watch on ngModel, or by using ngChange, but I've yet to understand how to detect a change to ngModel in Angular 2.
Full Example: http://plnkr.co/edit/9c9oKH1tjDDb67zdKmr9?p=info
import {Component, View, Input, } from 'angular2/core';
import {FORM_DIRECTIVES} from 'angular2/common';
#Component({
selector: 'my-dropdown'
})
#View({
directives: [FORM_DIRECTIVES],
template: `
<select [ngModel]="selection" (ngModelChange)="onChange($event, selection)" >
<option *ngFor="#option of options">{{option}}</option>
</select>
{{selection}}
`
})
export class MyDropdown {
#Input() options;
selection = 'Dog';
ngOnInit() {
console.log('These were the options passed in: ' + this.options);
}
onChange(event) {
if (this.selection === event) return;
this.selection = event;
console.log(this.selection);
}
}
As we can see, if we select a different value from the dropdown, our ngModel changes, and the interpolated expression in the view reflects this.
How do I get notified of this change in my class/controller?

Update:
Separate the event and property bindings:
<select [ngModel]="selectedItem" (ngModelChange)="onChange($event)">
onChange(newValue) {
console.log(newValue);
this.selectedItem = newValue; // don't forget to update the model here
// ... do other stuff here ...
}
You could also use
<select [(ngModel)]="selectedItem" (ngModelChange)="onChange($event)">
and then you wouldn't have to update the model in the event handler, but I believe this causes two events to fire, so it is probably less efficient.
Old answer, before they fixed a bug in beta.1:
Create a local template variable and attach a (change) event:
<select [(ngModel)]="selectedItem" #item (change)="onChange(item.value)">
plunker
See also How can I get new selection in "select" in Angular 2?

I have stumbled across this question and I will submit my answer that I used and worked pretty well. I had a search box that filtered and array of objects and on my search box I used the (ngModelChange)="onChange($event)"
in my .html
<input type="text" [(ngModel)]="searchText" (ngModelChange)="reSearch(newValue)" placeholder="Search">
then in my component.ts
reSearch(newValue: string) {
//this.searchText would equal the new value
//handle my filtering with the new value
}