Let's say I have two child components A and B
A has a button that should add a value to a grid select box column and B has the grid which has a vue select box for a column using
cellRenderer: 'tag-grid-select',
I want to be able to click on the button in A to refresh the select component in the grid in component B.
Note: This is not parent to child communication but child to child specifically using the Vue3 composition api and setup().
I was able to solve this using an eventbus. With this you can communicate with any component regardless of the relationship. I use npm package mitt
Here is some code I used for child to child communication
Component A -- contains ag-grid-vue
export default {
setup() {
return {
gridApi: null,
gridColumnApi: null,
}
},
async mounted() {
this.eventBus.on('refreshGrid', (args) => {
this.refreshGrid(args)
})
}
methods:
{
refreshGrid(params) {
this.gridApi.redrawRows()
},
async onGridReady(params) {
this.gridApi = params.api;
this.gridColumnApi = params.columnApi;
}
}
Component B - function that emits the command to be received by Component A
this.eventBus.emit('refreshGrid', {yourdata})
You will need to import and setup mitt according to their docs. I added it to my main.js so I did not have to import it in any page.
import mitt from 'mitt'
const eventBus = mitt()
app.config.globalProperties.eventBus = eventBus
I'm developing an app with Angular and Semantic-UI. The app should be accessible, this means it should be compliant with WCAG 2.0.
To reach this purpose the modals should keep focus within the dialog and prevents users from going outside or move with "tabs" between elements of the page that lays under the modal.
I have found some working examples, like the following:
JQuery dialog: https://jqueryui.com/dialog/#modal-confirmation
dialog HTML 5.1 element: https://demo.agektmr.com/dialog
ARIA modal dialog example:
http://w3c.github.io/aria-practices/examples/dialog-modal/dialog.html
(that I have reproduced on Plunker)
Here is my try to create an accessible modal with Semantic-UI: https://plnkr.co/edit/HjhkZg
As you can see I used the following attributes:
role="dialog"
aria-labelledby="modal-title"
aria-modal="true"
But they don't solve my issue. Do you know any way to make my modal keeping focus and lose it only when user click on cancel/confirm buttons?
There is currently no easy way to achieve this. The inert attribute was proposed to try to solve this problem by making any element with the attribute and all of it's children inaccessible. However, adoption has been slow and only recently did it land in Chrome Canary behind a flag.
Another proposed solution is making a native API that would keep track of the modal stack, essentially making everything not currently the top of the stack inert. I'm not sure the status of the proposal, but it doesn't look like it will be implemented any time soon.
So where does that leave us?
Unfortunately without a good solution. One solution that is popular is to create a query selector of all known focusable elements and then trap focus to the modal by adding a keydown event to the last and first elements in the modal. However, with the rise of web components and shadow DOM, this solution can no longer find all focusable elements.
If you always control all the elements within the dialog (and you're not creating a generic dialog library), then probably the easiest way to go is to add an event listener for keydown on the first and last focusable elements, check if tab or shift tab was used, and then focus the first or last element to trap focus.
If you're creating a generic dialog library, the only thing I have found that works reasonably well is to either use the inert polyfill or make everything outside of the modal have a tabindex=-1.
var nonModalNodes;
function openDialog() {
var modalNodes = Array.from( document.querySelectorAll('dialog *') );
// by only finding elements that do not have tabindex="-1" we ensure we don't
// corrupt the previous state of the element if a modal was already open
nonModalNodes = document.querySelectorAll('body *:not(dialog):not([tabindex="-1"])');
for (var i = 0; i < nonModalNodes.length; i++) {
var node = nonModalNodes[i];
if (!modalNodes.includes(node)) {
// save the previous tabindex state so we can restore it on close
node._prevTabindex = node.getAttribute('tabindex');
node.setAttribute('tabindex', -1);
// tabindex=-1 does not prevent the mouse from focusing the node (which
// would show a focus outline around the element). prevent this by disabling
// outline styles while the modal is open
// #see https://www.sitepoint.com/when-do-elements-take-the-focus/
node.style.outline = 'none';
}
}
}
function closeDialog() {
// close the modal and restore tabindex
if (this.type === 'modal') {
document.body.style.overflow = null;
// restore or remove tabindex from nodes
for (var i = 0; i < nonModalNodes.length; i++) {
var node = nonModalNodes[i];
if (node._prevTabindex) {
node.setAttribute('tabindex', node._prevTabindex);
node._prevTabindex = null;
}
else {
node.removeAttribute('tabindex');
}
node.style.outline = null;
}
}
}
The different "working examples" do not work as expected with a screenreader.
They do not trap the screenreader visual focus inside the modal.
For this to work, you have to :
Set the aria-hidden attribute on any other nodes
disable keyboard focusable elements inside those trees (links using tabindex=-1, controls using disabled, ...)
The jQuery :focusable pseudo selector can be useful to find focusable elements.
add a transparent layer over the page to disable mouse selection.
or you can use the css pointer-events: none property when the browser handles it with non SVG elements, not in IE
This focus-trap plugin is excellent at making sure that focus stays trapped inside of dialogue elements.
It sounds like your problem can be broken down into 2 categories:
focus on dialog box
Add a tabindex of -1 to the main container which is the DOM element that has role="dialog". Set the focus to the container.
wrapping the tab key
I found no other way of doing this except by getting the tabbable elements within the dialog box and listening it on keydown. When I know the element in focus (document.activeElement) is the last one on the list, I make it wrap
"focus" events can be intercepted in the capture phase, so you can listen for them at the document.body level, squelch them before they reach the target element, and redirect focus back to a control in your modal dialog. This example assumes a modal dialog with an input element gets displayed and assigned to the variable currDialog:
document.body.addEventListener("focus", (event) => {
if (currDialog && !currDialog.contains(event.target)) {
event.preventDefault();
event.stopPropagation();
currDialog.querySelector("input").focus();
}
}, {capture: true});
You may also want to contain such a dialog in a fixed-position, clear (or low-opacity) backdrop element that takes up the full screen in order to capture and suppress mouse/pointer events, so that no browser feedback (hover, etc.) occurs that could give the user the impression that the background is active.
Don't use any solution requiring you to look up "tabbable" elements. Instead, use keydown and either click events or a backdrop in an effective manor.
(Angular1)
See Asheesh Kumar's answer at https://stackoverflow.com/a/31292097/1754995 for something similar to what I am going for below.
(Angular2-x, I haven't done Angular1 in a while)
Say you have 3 components: BackdropComponent, ModalComponent (has an input), and AppComponent (has an input, the BackdropComponent, and the ModalComponent). You display BackdropComponent and ModalComponent with the correct z-index, both are currently displayed/visible.
What you need to do is have a general window.keydown event with preventDefault() to stop all tabbing when the backdrop/modal component is displayed. I recommend you put that on a BackdropComponent. Then you need a keydown.tab event with stopPropagation() to handle tabbing for the ModalComponent. Both the window.keydown and keydown.tab could probably be in the ModalComponent but there is purpose in a BackdropComponent further than just modals.
This should prevent clicking and tabbing to the AppComponent input and only click or tab to the ModalComponent input [and browser stuffs] when the modal is shown.
If you don't want to use a backdrop to prevent clicking, you can use use click events similarly to the keydown events described above.
Backdrop Component:
#Component({
selector: 'my-backdrop',
host: {
'tabindex': '-1',
'(window:keydown)': 'preventTabbing($event)'
},
...
})
export class BackdropComponent {
...
private preventTabbing(event: KeyboardEvent) {
if (event.keyCode === 9) { // && backdrop shown?
event.preventDefault();
}
}
...
}
Modal Component:
#Component({
selector: 'my-modal',
host: {
'tabindex': '-1',
'(keydown.tab)': 'onTab($event)'
},
...
})
export class ModalComponent {
...
private onTab(event: KeyboardEvent) {
event.stopPropagation();
}
...
}
Here's my solution. It traps Tab or Shift+Tab as necessary on first/last element of modal dialog (in my case found with role="dialog"). Eligible elements being checked are all visible input controls whose HTML may be input,select,textarea,button.
$(document).on('keydown', function(e) {
var target = e.target;
var shiftPressed = e.shiftKey;
// If TAB key pressed
if (e.keyCode == 9) {
// If inside a Modal dialog (determined by attribute role="dialog")
if ($(target).parents('[role=dialog]').length) {
// Find first or last input element in the dialog parent (depending on whether Shift was pressed).
// Input elements must be visible, and can be Input/Select/Button/Textarea.
var borderElem = shiftPressed ?
$(target).closest('[role=dialog]').find('input:visible,select:visible,button:visible,textarea:visible').first()
:
$(target).closest('[role=dialog]').find('input:visible,select:visible,button:visible,textarea:visible').last();
if ($(borderElem).length) {
if ($(target).is($(borderElem))) {
return false;
} else {
return true;
}
}
}
}
return true;
});
we can use the focus trap npm package.
npm i focus-trap
This might help someone who is looking for solution in Angular.
Step 1: Add keydown event on dialog component
#HostListener('document:keydown', ['$event'])
handleTabKeyWInModel(event: any) {
this.sharedService.handleTabKeyWInModel(event, '#modal_id', this.elementRef.nativeElement, 'input,button,select,textarea,a,[tabindex]:not([tabindex="-1"])');
}
This will filters the elements which are preseneted in the Modal dialog.
Step 2: Add common method to handle focus in shared service (or you can add it in your component as well)
handleTabKeyWInModel(e, modelId: string, nativeElement, tagsList: string) {
if (e.keyCode === 9) {
const focusable = nativeElement.querySelector(modelId).querySelectorAll(tagsList);
if (focusable.length) {
const first = focusable[0];
const last = focusable[focusable.length - 1];
const shift = e.shiftKey;
if (shift) {
if (e.target === first) { // shift-tab pressed on first input in dialog
last.focus();
e.preventDefault();
}
} else {
if (e.target === last) { // tab pressed on last input in dialog
first.focus();
e.preventDefault();
}
}
}
}
}
Now this method will take the modal dialog native element and start evaluate on every tab key. Finally we will filter the event on first and last so that we can focus on appropriate elements (on first after last element tab click and on last shift+tab event on first element).
Happy Coding.. :)
I used one of the methods suggested by Steven Lambert, namely, listening to keydown events and intercepting "tab" and "shift+tab" keys. Here's my sample code (Angular 5):
import { Directive, ElementRef, Attribute, HostListener, OnInit } from '#angular/core';
/**
* This directive allows to override default tab order for page controls.
* Particularly useful for working around the modal dialog TAB issue
* (when tab key allows to move focus outside of dialog).
*
* Usage: add "custom-taborder" and "tab-next='next_control'"/"tab-prev='prev_control'" attributes
* to the first and last controls of the dialog.
*
* For example, the first control is <input type="text" name="ctlName">
* and the last one is <button type="submit" name="btnOk">
*
* You should modify the above declarations as follows:
* <input type="text" name="ctlName" custom-taborder tab-prev="btnOk">
* <button type="submit" name="btnOk" custom-taborder tab-next="ctlName">
*/
#Directive({
selector: '[custom-taborder]'
})
export class CustomTabOrderDirective {
private elem: HTMLInputElement;
private nextElemName: string;
private prevElemName: string;
private nextElem: HTMLElement;
private prevElem: HTMLElement;
constructor(
private elemRef: ElementRef
, #Attribute('tab-next') public tabNext: string
, #Attribute('tab-prev') public tabPrev: string
) {
this.elem = this.elemRef.nativeElement;
this.nextElemName = tabNext;
this.prevElemName = tabPrev;
}
ngOnInit() {
if (this.nextElemName) {
var elems = document.getElementsByName(this.nextElemName);
if (elems && elems.length && elems.length > 0)
this.nextElem = elems[0];
}
if (this.prevElemName) {
var elems = document.getElementsByName(this.prevElemName);
if (elems && elems.length && elems.length > 0)
this.prevElem = elems[0];
}
}
#HostListener('keydown', ['$event'])
onKeyDown(event: KeyboardEvent) {
if (event.key !== "Tab")
return;
if (!event.shiftKey && this.nextElem) {
this.nextElem.focus();
event.preventDefault();
}
if (event.shiftKey && this.prevElem) {
this.prevElem.focus();
event.preventDefault();
}
}
}
To use this directive, just import it to your module and add to Declarations section.
I've been successful using Angular Material's A11yModule.
Using your favorite package manager install these to packages into your Angular app.
**"#angular/material": "^10.1.2"**
**"#angular/cdk": "^10.1.2"**
In your Angular module where you import the Angular Material modules add this:
**import {A11yModule} from '#angular/cdk/a11y';**
In your component HTML apply the cdkTrapFocus directive to any parent element, example: div, form, etc.
Run the app, tabbing will now be contained within the decorated parent element.
For jquery users:
Assign role="dialog" to your modal
Find first and last interactive element inside the dialog modal.
Check if current target is one of them(depending on shift key is
pressed or not).
If target element is one of first or last interactive element of the
dialog, return false
Working code sample:
//on keydown inside dialog
$('.modal[role=dialog]').on('keydown', e => {
let target = e.target;
let shiftPressed = e.shiftKey;
// If TAB is pressed
if (e.keyCode === 9) {
// Find first and last element in the ,modal-dialog parent.
// Elements must be interactive i.e. visible, and can be Input/Select/Button/Textarea.
let first = $(target).closest('[role=dialog]').find('input:visible,select:visible,button:visible,textarea:visible').first();
let last = $(target).closest('[role=dialog]').find('input:visible,select:visible,button:visible,textarea:visible').last();
let borderElem = shiftPressed ? first : last //border element on the basis of shift key pressed
if ($(borderElem).length) {
return !$(target).is($(borderElem)); //if target is border element , return false
}
}
return true;
});
I read through most of the answers, while the package focus-trap seems like a good option. #BenVida shared a very simple VanillaJS solution here in another Stack Overflow post.
Here is the code:
const container=document.querySelector("_selector_for_the_container_")
//optional: needed only if the container element is not focusable already
container.setAttribute("tabindex","0")
container.addEventListener("focusout", (ev)=>{
if (!container.contains(ev.relatedTarget)) container.focus()
})
I am creating an Anchor as follows:
Anchor a = new Anchor( "Click Me" );
Then I add a click handler:
a.addClickHandler( new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
GWT.log("Anchor Clicked");
}
} );
I want to add the Anchor to a LI element. Since I don't have any Widgets for UL and LI, I use the following construct:
public class ElementPanel extends ComplexPanel {
public ElementPanel(String tagName) {
setElement(DOM.createElement(tagName));
}
#Override
public void add(Widget w) {
add(w, getElement());
}
}
I create my UL element:
ElementPanel ul = new ElementPanel(UListElement.TAG);
I create a LI element:
ElementPanel li = new ElementPanel(LIElement.TAG);
I add my Anchor to LI, then I add LI to UL (after which I add to the document):
li.add(a);
ul.add(li);
This works fine. If instead I change the previous lines as follows, I don't see a log message:
li.getElement().appendChild(a.getElement());
ul.add(li);
Similarly, if instead I try this, I also do not see a message:
li.add(a);
ul.getElement().appendChild(li.getElement());
Previously, I had the UL element in the UIBinder. But since I was not successful in adding a click handler to an Element, I have to resort to the above approach.
This is how events are handled in GWT: the widget needs to be attached, and that generally means adding it to a container chain up to a RootPanel. See https://code.google.com/p/google-web-toolkit/wiki/DomEventsAndMemoryLeaks#GWT's_Solution for the details.
The easiest way to have <ul><li> if your structure doesn't change dynamically is to use an HTMLPanel (and it's even easier with UiBinder).
If the structure is dynamic, then possibly make a ComplexPanel whose root element is a UListElement and which wraps all child widgets into a LIElement. Have a look at the internals of ComplexPanel, you'll see that it attaches and detaches the child widgets whenever they are added/removed while the panel itself is attached, or whenever the panel is attached / detached.
I have two ViewModels in my MVVM app. the one is bind to main window and another to popup window which appears after click on the button. in the popup window I need binding to the selected entity from main window. how can I access this entity in MainViewModel from PopupViewModel?
ZK has the concept of the event queue and global commands for communication between multiple ViewModels so we can use that to pass the current selected entity to the ViewModel of a popup window.
Using this zk mvvm demo page:
(see docs)
I added to the listbox a global command which fires out the current selected reminder of the main ViewModel which needs to be shown by a popup window:
<listbox id="list" multiple="true" rows="6"
model="#load(vm.reminders)"
selectedItem="#bind(vm.selectedReminder)"
onSelect="#global-command('refresh', reminder=vm.selectedReminder)">
Then I added to the bottom of the page a popup window with a second ViewModel:
<window id="info" visible="false" width="120px" border="normal" position="parent"
apply="org.zkoss.bind.BindComposer"
viewModel="#id('vm') #init('org.zkforge.zktodo2.ui.ViewModelPopup')"
>
You have selected <label value="#load(vm.currentReminder.name)"/>
</window>
<button label="More info" onClick="info.doPopup()"/>
</zk>
The pop up Viewmodel has a method which accepts the global command which takes the entity as a parameter:
public class ViewModelPopup {
protected Reminder currentReminder = new Reminder();
public Reminder getCurrentReminder() {
return currentReminder;
}
public void setCurrentReminder(Reminder currentReminder) {
this.currentReminder = currentReminder;
}
#GlobalCommand #NotifyChange("currentReminder")
public void refresh(#BindingParam("reminder") Reminder reminder ){
this.setCurrentReminder(reminder);
return;
}
}
So now whenever you select an item in the listbox the refresh method is fired on the popup ViewModel passing into it data taken from the main ViewModel. Whenever you hit the "More info" button at the bottom of the page to show the popup window it displays the name of the current selected entity.
The documentation which I followed to do this is at:
(docs1)
(docs2)
The instructions to run that sample app are on the readme at (Docs3)
Do you have a list of entities in your mainwindow? if that is the case, from the view model of your main window you need to put your selected entity in a map and pass it as a param for createComponents just like this:
//In the view Model of the main window
Map arg = new HashMap();
arg.put("selectedEntity", SelectedEntity);
Executions.createComponents("/myPopup.zul", null, arg);
Now in the popup view model, you simply retrieve the value of your Entity in the Init method:
//PopupView model
#Init
public void init(#ExecutionArgParam("selectedEntity") SelectedEntity newEntity) {
entity = newEntity;
}
you can notice that the string in ExecutionArgParam is the key you put in the map.
We're using gwt-presenter, but not really a question specific to that...
I've got a table with users in it. As I build the table in the view (from the data provided by the presenter), I need to add two action buttons ("Edit", and "Delete") at the end of the row.
What's the best way to assign click handlers to these buttons so the presenter knows which was clicked? Previous to this, we could pass a private field from the view to the presenter and attach a discrete click handler to that button. However, this method is rather rigid and doesn't work in this scenario very well.
Thanks in advance.
How about having the view allowing the subscription for edit/delete click events, registering internally the individual row click events, and then delegating the event handling to the ones registered by the view?
I mean something like the following pesudo code:
View:
addRowEditClickHandler(ClickHandler handler) {
this.rowEditClickHandler = handler;
}
addRowDeleteClickHandler(ClickHandler handler) {
this.rowDeleteClickHandler = handler;
}
//... somewhere when setting up of the grid...
rowEditButton.addClickHandler = new ClickHandler() {
onClick(args) {
this.rowEditClickHandler.onClick(args)
}
rowDeleteButton.addClickHandler = new ClickHandler() {
onClick(args) {
this.rowDeleteClickHandler.onClick(args)
}
Presenter:
View view = new View();
view.addRowEditClickHandler( new ClickHandler() {
onClick(args) {
doSomething();
}
});
view.addRowDeleteClickHandler( new ClickHandler() {
onClick(args) {
doSomething();
}
});